View Full Version : Q: Calibrating a 1962 CD Radiation Meter
Norm Dresner
Jun27-04, 06:02 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Among the stuff in my father-in-law\'s basement I found a \'1962 "Radiological\nSurvey Meter" which the manual says is only sensitive to gamma radiation.\n"It is designed to be used by radiological Civil Defense personnel\nin determining radioactive contamination levels that may result from an\nenemy attack or other nuclear disasters."\n\nIt\'s claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".\nAfter changing the battery -- astoundingly for that era it\'s a single\npentode hybrid vacuum tube & single transistor circuit that runs on a\nsingle D-cell -- it passed it\'s built in self-check which, according to the\nschematic, just assures that the electronic circuitry is working close to\nits design point. Since I\'m not in a university and don\'t have any "radium\nor Cobalt 60" laying around the house (AFAIK), I\'m stumped as to finding a\nmethod of determining if this thing still works. I\'d appreciate suggestions\nfor either a Q&D function-test or a real calibration with a safe source of\naround 4 r/hr of gamma radiation.\n\nTIA\nNorm\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Among the stuff in my father-in-law's basement I found a '1962 "Radiological
Survey Meter" which the manual says is only sensitive to \gamma radiation.
"It is designed to be used by radiological Civil Defense personnel
in determining radioactive contamination levels that may result from an
enemy attack or other nuclear disasters."
It's claimed sensitivity runs from around .2 to 500 "roentgens per hour".
After changing the battery -- astoundingly for that era it's a single
pentode hybrid vacuum tube & single transistor circuit that runs on a
single D-cell -- it passed it's built in self-check which, according to the
schematic, just assures that the electronic circuitry is working close to
its design point. Since I'm not in a university and don't have any "radium
or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
method of determining if this thing still works. I'd appreciate suggestions
for either a Q&D function-test or a real calibration with a safe source of
around 4 r/hr of \gamma radiation.
TIA
Norm
Michael Dombrowski
Jun29-04, 05:47 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Norm Dresner wrote:\n> Among the stuff in my father-in-law\'s basement I found a \'1962 "Radiological\n> Survey Meter" which the manual says is only sensitive to gamma radiation.\n> "It is designed to be used by radiological Civil Defense personnel\n> in determining radioactive contamination levels that may result from an\n> enemy attack or other nuclear disasters."\n>\n> It\'s claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".\n> After changing the battery -- astoundingly for that era it\'s a single\n> pentode hybrid vacuum tube & single transistor circuit that runs on a\n> single D-cell -- it passed it\'s built in self-check which, according to the\n> schematic, just assures that the electronic circuitry is working close to\n> its design point. Since I\'m not in a university and don\'t have any "radium\n> or Cobalt 60" laying around the house (AFAIK), I\'m stumped as to finding a\n> method of determining if this thing still works. I\'d appreciate suggestions\n> for either a Q&D function-test or a real calibration with a safe source of\n> around 4 r/hr of gamma radiation.\n>\n> TIA\n> Norm\n>\n\nI certainly am no expert in radiation meters, but I seem to recall\nradioactive marbles on Ebay mentioned in conjunction with calibration.\nMaybe you could check that out?\n\nMike\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Norm Dresner wrote:
> Among the stuff in my father-in-law's basement I found a '1962 "Radiological
> Survey Meter" which the manual says is only sensitive to \gamma radiation.
> "It is designed to be used by radiological Civil Defense personnel
> in determining radioactive contamination levels that may result from an
> enemy attack or other nuclear disasters."
>
> It's claimed sensitivity runs from around .2 to 500 "roentgens per hour".
> After changing the battery -- astoundingly for that era it's a single
> pentode hybrid vacuum tube & single transistor circuit that runs on a
> single D-cell -- it passed it's built in self-check which, according to the
> schematic, just assures that the electronic circuitry is working close to
> its design point. Since I'm not in a university and don't have any "radium
> or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
> method of determining if this thing still works. I'd appreciate suggestions
> for either a Q&D function-test or a real calibration with a safe source of
> around 4 r/hr of \gamma radiation.
>
> TIA
> Norm
>
I certainly am no expert in radiation meters, but I seem to recall
radioactive marbles on Ebay mentioned in conjunction with calibration.
Maybe you could check that out?
Mike
Robert Baer
Jun29-04, 05:48 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nNorm Dresner wrote:\n>\n> Among the stuff in my father-in-law\'s basement I found a \'1962 "Radiological\n> Survey Meter" which the manual says is only sensitive to gamma radiation.\n> "It is designed to be used by radiological Civil Defense personnel\n> in determining radioactive contamination levels that may result from an\n> enemy attack or other nuclear disasters."\n>\n> It\'s claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".\n> After changing the battery -- astoundingly for that era it\'s a single\n> pentode hybrid vacuum tube & single transistor circuit that runs on a\n> single D-cell -- it passed it\'s built in self-check which, according to the\n> schematic, just assures that the electronic circuitry is working close to\n> its design point. Since I\'m not in a university and don\'t have any "radium\n> or Cobalt 60" laying around the house (AFAIK), I\'m stumped as to finding a\n> method of determining if this thing still works. I\'d appreciate suggestions\n> for either a Q&D function-test or a real calibration with a safe source of\n> around 4 r/hr of gamma radiation.\n>\n> TIA\n> Norm\n\nYour best bet would seem to go to a university "nearby" after calling\nto be sure they have sources for the sensitivity check.\nAs long as the GM tube is still OK, the instrument should be fairly\nclose.\nThis could be considered a type of collectors item; keep it!\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Norm Dresner wrote:
>
> Among the stuff in my father-in-law's basement I found a '1962 "Radiological
> Survey Meter" which the manual says is only sensitive to \gamma radiation.
> "It is designed to be used by radiological Civil Defense personnel
> in determining radioactive contamination levels that may result from an
> enemy attack or other nuclear disasters."
>
> It's claimed sensitivity runs from around .2 to 500 "roentgens per hour".
> After changing the battery -- astoundingly for that era it's a single
> pentode hybrid vacuum tube & single transistor circuit that runs on a
> single D-cell -- it passed it's built in self-check which, according to the
> schematic, just assures that the electronic circuitry is working close to
> its design point. Since I'm not in a university and don't have any "radium
> or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
> method of determining if this thing still works. I'd appreciate suggestions
> for either a Q&D function-test or a real calibration with a safe source of
> around 4 r/hr of \gamma radiation.
>
> TIA
> Norm
Your best bet would seem to go to a university "nearby" after calling
to be sure they have sources for the sensitivity check.
As long as the GM tube is still OK, the instrument should be fairly
close.
This could be considered a type of collectors item; keep it!
Robert Baer
Jun29-04, 05:49 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nNorm Dresner wrote:\n>\n> Among the stuff in my father-in-law\'s basement I found a \'1962 "Radiological\n> Survey Meter" which the manual says is only sensitive to gamma radiation.\n> "It is designed to be used by radiological Civil Defense personnel\n> in determining radioactive contamination levels that may result from an\n> enemy attack or other nuclear disasters."\n>\n> It\'s claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".\n> After changing the battery -- astoundingly for that era it\'s a single\n> pentode hybrid vacuum tube & single transistor circuit that runs on a\n> single D-cell -- it passed it\'s built in self-check which, according to the\n> schematic, just assures that the electronic circuitry is working close to\n> its design point. Since I\'m not in a university and don\'t have any "radium\n> or Cobalt 60" laying around the house (AFAIK), I\'m stumped as to finding a\n> method of determining if this thing still works. I\'d appreciate suggestions\n> for either a Q&D function-test or a real calibration with a safe source of\n> around 4 r/hr of gamma radiation.\n>\n> TIA\n> Norm\n\nYour best bet would seem to go to a university "nearby" after calling\nto be sure they have sources for the sensitivity check.\nAs long as the GM tube is still OK, the instrument should be fairly\nclose.\nThis could be considered a type of collectors item; keep it!\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Norm Dresner wrote:
>
> Among the stuff in my father-in-law's basement I found a '1962 "Radiological
> Survey Meter" which the manual says is only sensitive to \gamma radiation.
> "It is designed to be used by radiological Civil Defense personnel
> in determining radioactive contamination levels that may result from an
> enemy attack or other nuclear disasters."
>
> It's claimed sensitivity runs from around .2 to 500 "roentgens per hour".
> After changing the battery -- astoundingly for that era it's a single
> pentode hybrid vacuum tube & single transistor circuit that runs on a
> single D-cell -- it passed it's built in self-check which, according to the
> schematic, just assures that the electronic circuitry is working close to
> its design point. Since I'm not in a university and don't have any "radium
> or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
> method of determining if this thing still works. I'd appreciate suggestions
> for either a Q&D function-test or a real calibration with a safe source of
> around 4 r/hr of \gamma radiation.
>
> TIA
> Norm
Your best bet would seem to go to a university "nearby" after calling
to be sure they have sources for the sensitivity check.
As long as the GM tube is still OK, the instrument should be fairly
close.
This could be considered a type of collectors item; keep it!
Liui Ganishiapu
Jun29-04, 05:50 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>You can buy some items from ebay to test with. If you are getting a click or\ntwo per min, it is picking up background radiation, which means it is\nworking good. Many meters back then were for post necular war, which means\nthey only regester very high levels of radiation, which you don\'t want to be\naround anyway. Do you have a make and model # on it?\n\n"Norm Dresner" <ndrez@att.net> wrote in message\nnews:gB%Bc.17018\\$OB3.13478@bgtnsc05-news.ops.worldnet.att.net...\n> Among the stuff in my father-in-law\'s basement I found a \'1962\n"Radiological\n> Survey Meter" which the manual says is only sensitive to gamma radiation.\n> "It is designed to be used by radiological Civil Defense personnel\n> in determining radioactive contamination levels that may result from an\n> enemy attack or other nuclear disasters."\n>\n> It\'s claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".\n> After changing the battery -- astoundingly for that era it\'s a single\n> pentode hybrid vacuum tube & single transistor circuit that runs on a\n> single D-cell -- it passed it\'s built in self-check which, according to\nthe\n> schematic, just assures that the electronic circuitry is working close to\n> its design point. Since I\'m not in a university and don\'t have any\n"radium\n> or Cobalt 60" laying around the house (AFAIK), I\'m stumped as to finding a\n> method of determining if this thing still works. I\'d appreciate\nsuggestions\n> for either a Q&D function-test or a real calibration with a safe source of\n> around 4 r/hr of gamma radiation.\n>\n> TIA\n> Norm\n>\n\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>You can buy some items from ebay to test with. If you are getting a click or
two per min, it is picking up background radiation, which means it is
working good. Many meters back then were for post necular war, which means
they only regester very high levels of radiation, which you don't want to be
around anyway. Do you have a make and model # on it?
"Norm Dresner" <ndrez@att.net> wrote in message
news:gB%Bc.17018$OB3.13478@bgtnsc05-news.ops.worldnet.att.net...
> Among the stuff in my father-in-law's basement I found a '1962
"Radiological
> Survey Meter" which the manual says is only sensitive to \gamma radiation.
> "It is designed to be used by radiological Civil Defense personnel
> in determining radioactive contamination levels that may result from an
> enemy attack or other nuclear disasters."
>
> It's claimed sensitivity runs from around .2 to 500 "roentgens per hour".
> After changing the battery -- astoundingly for that era it's a single
> pentode hybrid vacuum tube & single transistor circuit that runs on a
> single D-cell -- it passed it's built in self-check which, according to
the
> schematic, just assures that the electronic circuitry is working close to
> its design point. Since I'm not in a university and don't have any
"radium
> or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
> method of determining if this thing still works. I'd appreciate
suggestions
> for either a Q&D function-test or a real calibration with a safe source of
> around 4 r/hr of \gamma radiation.
>
> TIA
> Norm
>
Jon Elson
Jun29-04, 05:58 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nNorm Dresner wrote:\n\n>Among the stuff in my father-in-law\'s basement I found a \'1962 "Radiological\n>Survey Meter" which the manual says is only sensitive to gamma radiation.\n> "It is designed to be used by radiological Civil Defense personnel\n>in determining radioactive contamination levels that may result from an\n>enemy attack or other nuclear disasters."\n>\n>It\'s claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".\n>After changing the battery -- astoundingly for that era it\'s a single\n>pentode hybrid vacuum tube & single transistor circuit that runs on a\n>single D-cell -- it passed it\'s built in self-check which, according to the\n>schematic, just assures that the electronic circuitry is working close to\n>its design point. Since I\'m not in a university and don\'t have any "radium\n>or Cobalt 60" laying around the house (AFAIK), I\'m stumped as to finding a\n>method of determining if this thing still works. I\'d appreciate suggestions\n>for either a Q&D function-test or a real calibration with a safe source of\n>around 4 r/hr of gamma radiation.\n>\n>\nI\'m guessing, from the description, that this is an ionization chamber,\nnot a\nGeiger-Muller tube detector. There were dinner plates made in the 70\'s with\na VERY bright orange glaze made from Uranium. They were recalled, but\nsome people have kept them around. If you can find one of these at a flea\nmarket, even a small chip will easily trigger a Geiger counter. A whole\nplate should be able to give a reading on even a poor ionization chamber\ndetector.\n\nAnother common radiation source is a gas mantle, as in yard lamps and\nColeman lanterns. They have thorium in them. Thoriated Tungsten TIG\nelectrodes are also radioactive. (I can\'t remember if this is a Gamma\nsource or not, though.)\n\nEven household bricks are weak radiation sources, but I suspect way too\nweak for such a detector to pick up.\n\nThe Geiger-tube detectors usually have a small label on the side marked\n"test detector here", which has a suitable source for checking the detector.\nThe ion chamber units are usually one-piece, so a test source would be\nhard to provide, but you might look around and see if there is such a\nlabel present.\n\nJon\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Norm Dresner wrote:
>Among the stuff in my father-in-law's basement I found a '1962 "Radiological
>Survey Meter" which the manual says is only sensitive to \gamma radiation.
> "It is designed to be used by radiological Civil Defense personnel
>in determining radioactive contamination levels that may result from an
>enemy attack or other nuclear disasters."
>
>It's claimed sensitivity runs from around .2 to 500 "roentgens per hour".
>After changing the battery -- astoundingly for that era it's a single
>pentode hybrid vacuum tube & single transistor circuit that runs on a
>single D-cell -- it passed it's built in self-check which, according to the
>schematic, just assures that the electronic circuitry is working close to
>its design point. Since I'm not in a university and don't have any "radium
>or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
>method of determining if this thing still works. I'd appreciate suggestions
>for either a Q&D function-test or a real calibration with a safe source of
>around 4 r/hr of \gamma radiation.
>
>
I'm guessing, from the description, that this is an ionization chamber,
not a
Geiger-Muller tube detector. There were dinner plates made in the 70's with
a VERY bright orange glaze made from Uranium. They were recalled, but
some people have kept them around. If you can find one of these at a flea
market, even a small chip will easily trigger a Geiger counter. A whole
plate should be able to give a reading on even a poor ionization chamber
detector.
Another common radiation source is a gas mantle, as in yard lamps and
Coleman lanterns. They have thorium in them. Thoriated Tungsten TIG
electrodes are also radioactive. (I can't remember if this is a \Gamma
source or not, though.)
Even household bricks are weak radiation sources, but I suspect way too
weak for such a detector to pick up.
The Geiger-tube detectors usually have a small label on the side marked
"test detector here", which has a suitable source for checking the detector.
The ion chamber units are usually one-piece, so a test source would be
hard to provide, but you might look around and see if there is such a
label present.
Jon
David Williams
Jun30-04, 05:40 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>-> Another common radiation source is a gas mantle, as in yard lamps and\n-> Coleman lanterns. They have thorium in them. Thoriated Tungsten TIG\n-> electrodes are also radioactive. (I can\'t remember if this is a Gamma\n-> source or not, though.)\n\n-> Even household bricks are weak radiation sources, but I suspect way too\n-> weak for such a detector to pick up.\n\nMost cheap smoke alarms contain a small amount of radioactive\nmaterial. I have never tried measuring the radiation they produce, but\nit should be detectable.\n\nOld instruments with luminous dials - even wristwatches - contain small\namounts of radium, the radiation from which keeps the phosphor glowing\neven after long periods in darkness. Nowadays, this is considered too\nhazardous, but plenty of the old dials still exist, and can be used as\nradiation sources.\n\ndow\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>-> Another common radiation source is a gas mantle, as in yard lamps and
-> Coleman lanterns. They have thorium in them. Thoriated Tungsten TIG
-> electrodes are also radioactive. (I can't remember if this is a \Gamma
-> source or not, though.)
-> Even household bricks are weak radiation sources, but I suspect way too
-> weak for such a detector to pick up.
Most cheap smoke alarms contain a small amount of radioactive
material. I have never tried measuring the radiation they produce, but
it should be detectable.
Old instruments with luminous dials - even wristwatches - contain small
amounts of radium, the radiation from which keeps the phosphor glowing
even after long periods in darkness. Nowadays, this is considered too
hazardous, but plenty of the old dials still exist, and can be used as
radiation sources.
dow
eagleson2004123@yahoo.com
Jun30-04, 05:41 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>"Norm Dresner" <ndrez@att.net> wrote in message news:<gB%Bc.17018\\$OB3.13478@bgtnsc05-news.ops.worldnet.att.net>...\n> Among the stuff in my father-in-law\'s basement I found a \'1962 "Radiological\n> Survey Meter" which the manual says is only sensitive to gamma radiation.\n> "It is designed to be used by radiological Civil Defense personnel\n> in determining radioactive contamination levels that may result from an\n> enemy attack or other nuclear disasters."\n>\n> It\'s claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".\n> After changing the battery -- astoundingly for that era it\'s a single\n> pentode hybrid vacuum tube & single transistor circuit that runs on a\n> single D-cell -- it passed it\'s built in self-check which, according to the\n> schematic, just assures that the electronic circuitry is working close to\n> its design point. Since I\'m not in a university and don\'t have any "radium\n> or Cobalt 60" laying around the house (AFAIK), I\'m stumped as to finding a\n> method of determining if this thing still works. I\'d appreciate suggestions\n> for either a Q&D function-test or a real calibration with a safe source of\n> around 4 r/hr of gamma radiation.\n>\n> TIA\n> Norm\n\n\nYour meter is not the low level training type. It is the actual\nusage kind.\n\nCalibration is expensive. A few hundred dollars at a commercial laboratory\nI would guess.\n\nIf you live near a nuclar power plant you could run after\na radioactive waste hauling truck and try to get it calibrated to the\ntrucks postings???? Stay cool looking when you do this though, beccause\nyou just might be mistaken for a bad guy.\n\nAnyways, nothing in common use in the consumer realm is radioactive\nenough to give an indication. You are just out of luck.\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>"Norm Dresner" <ndrez@att.net> wrote in message news:<gB%Bc.17018$OB3.13478@bgtnsc05-news.ops.worldnet.att.net>...
> Among the stuff in my father-in-law's basement I found a '1962 "Radiological
> Survey Meter" which the manual says is only sensitive to \gamma radiation.
> "It is designed to be used by radiological Civil Defense personnel
> in determining radioactive contamination levels that may result from an
> enemy attack or other nuclear disasters."
>
> It's claimed sensitivity runs from around .2 to 500 "roentgens per hour".
> After changing the battery -- astoundingly for that era it's a single
> pentode hybrid vacuum tube & single transistor circuit that runs on a
> single D-cell -- it passed it's built in self-check which, according to the
> schematic, just assures that the electronic circuitry is working close to
> its design point. Since I'm not in a university and don't have any "radium
> or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
> method of determining if this thing still works. I'd appreciate suggestions
> for either a Q&D function-test or a real calibration with a safe source of
> around 4 r/hr of \gamma radiation.
>
> TIA
> Norm
Your meter is not the low level training type. It is the actual
usage kind.
Calibration is expensive. A few hundred dollars at a commercial laboratory
I would guess.
If you live near a nuclar power plant you could run after
a radioactive waste hauling truck and try to get it calibrated to the
trucks postings???? Stay cool looking when you do this though, beccause
you just might be mistaken for a bad guy.
Anyways, nothing in common use in the consumer realm is radioactive
enough to give an indication. You are just out of luck.
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>"Norm Dresner" <ndrez@att.net> wrote in message news:<gB%Bc.17018\\$OB3.13478@bgtnsc05-news.ops.worldnet.att.net>...\n> Among the stuff in my father-in-law\'s basement I found a \'1962 "Radiological\n> Survey Meter" which the manual says is only sensitive to gamma radiation.\n> "It is designed to be used by radiological Civil Defense personnel\n> in determining radioactive contamination levels that may result from an\n> enemy attack or other nuclear disasters."\n>\n> It\'s claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".\n> After changing the battery -- astoundingly for that era it\'s a single\n> pentode hybrid vacuum tube & single transistor circuit that runs on a\n> single D-cell -- it passed it\'s built in self-check which, according to the\n> schematic, just assures that the electronic circuitry is working close to\n> its design point. Since I\'m not in a university and don\'t have any "radium\n> or Cobalt 60" laying around the house (AFAIK), I\'m stumped as to finding a\n> method of determining if this thing still works. I\'d appreciate suggestions\n> for either a Q&D function-test or a real calibration with a safe source of\n> around 4 r/hr of gamma radiation.\n>\n> TIA\n> Norm\n\nThe radioactive substance in smoke detectors is Am-241, but it is\ntiny. I am not sure if your detector would even be able to detect\nthat. But the most important thing for calibration is having a know\nquantity of disinigrations per sec or, 1 bequerel.\n\nYou also mentioned the Roentgen.\n\nThe Roentgen (R) is a unit used to measure a quantity called exposure.\nThis can only be used to describe an amount of gamma and X-rays, and\nonly in air. One roentgen is equal to depositing in dry air enough\nenergy to cause 2.58E-4 coulombs per kg. It is a measure of the\nionizations of the molecules in a mass of air. The main advantage of\nthis unit is that it is easy to measure directly, but it is limited\nbecause it is only for deposition in air, and only for gamma and x\nrays.\n\ndan\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>"Norm Dresner" <ndrez@att.net> wrote in message news:<gB%Bc.17018$OB3.13478@bgtnsc05-news.ops.worldnet.att.net>...
> Among the stuff in my father-in-law's basement I found a '1962 "Radiological
> Survey Meter" which the manual says is only sensitive to \gamma radiation.
> "It is designed to be used by radiological Civil Defense personnel
> in determining radioactive contamination levels that may result from an
> enemy attack or other nuclear disasters."
>
> It's claimed sensitivity runs from around .2 to 500 "roentgens per hour".
> After changing the battery -- astoundingly for that era it's a single
> pentode hybrid vacuum tube & single transistor circuit that runs on a
> single D-cell -- it passed it's built in self-check which, according to the
> schematic, just assures that the electronic circuitry is working close to
> its design point. Since I'm not in a university and don't have any "radium
> or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
> method of determining if this thing still works. I'd appreciate suggestions
> for either a Q&D function-test or a real calibration with a safe source of
> around 4 r/hr of \gamma radiation.
>
> TIA
> Norm
The radioactive substance in smoke detectors is Am-241, but it is
tiny. I am not sure if your detector would even be able to detect
that. But the most important thing for calibration is having a know
quantity of disinigrations per sec or, 1 bequerel.
You also mentioned the Roentgen.
The Roentgen (R) is a unit used to measure a quantity called exposure.
This can only be used to describe an amount of \gamma and X-rays, and
only in air. One roentgen is equal to depositing in dry air enough
energy to cause 2.58E-4 coulombs per kg. It is a measure of the
ionizations of the molecules in a mass of air. The main advantage of
this unit is that it is easy to measure directly, but it is limited
because it is only for deposition in air, and only for \gamma and x
rays.
dan
Bart Wessel
Jul2-04, 04:31 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nOn Sun, 27 Jun 2004 23:02:25 +0000 (UTC), "Norm Dresner"\n<ndrez@att.net> wrote:\n\n>I\'d appreciate suggestions\n>for either a Q&D function-test or a real calibration with a safe source of\n>around 4 r/hr of gamma radiation.\nNo need to buy your own radioactive source.\nPay your local fire department a friendly visit. They have meters and\na source to check them. If they are not out on a job, they\'ll probably\nwelcome the distraction from daily duties and take the oportunity to\nrestudy the subject.\nWell, that\'s what happened to me when I visited the guys here... Had a\nvery interesting lecture on the subject from the Chief! And yes, my\nmeter worked almost perfectly.\n\nBartW.\nBart.\n\nThere may be a \'NOSPAM.\' (mind the dot!) in front of my E-mail address.\nIt is there to fool machines, not people. Please remove it when you want to reply to me personally.\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Sun, 27 Jun 2004 23:02:25 +0000 (UTC), "Norm Dresner"
<ndrez@att.net> wrote:
>I'd appreciate suggestions
>for either a Q&D function-test or a real calibration with a safe source of
>around 4 r/hr of \gamma radiation.
No need to buy your own radioactive source.
Pay your local fire department a friendly visit. They have meters and
a source to check them. If they are not out on a job, they'll probably
welcome the distraction from daily duties and take the oportunity to
restudy the subject.
Well, that's what happened to me when I visited the guys here... Had a
very interesting lecture on the subject from the Chief! And yes, my
meter worked almost perfectly.
BartW.
Bart.
There may be a 'NOSPAM.' (mind the dot!) in front of my E-mail address.
It is there to fool machines, not people. Please remove it when you want to reply to me personally.
Norm Dresner
Jul2-04, 04:31 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n"Liui Ganishiapu" <void@invalid.com> wrote in message\nnews:2kb97qFb4thU1@uni-berlin.de...\n> You can buy some items from ebay to test with. If you are getting a click\nor\n> two per min, it is picking up background radiation, which means it is\n> working good. Many meters back then were for post necular war, which means\n> they only regester very high levels of radiation, which you don\'t want to\nbe\n> around anyway. Do you have a make and model # on it?\n>\nIt\'s a Victoreen Model 1A [also called a CD V-715] "designed to be used by\nradiological Civil Defense personnel in determining radioactive\ncontamination levels that may result from an enemy attack or other nulear\ndisasters."\n\nThe range of sensitivity is roughly .03 to 500 roentgens per hour and is\nsupposed to be sensitive to only gamma radiation. It contains a\n"hermetically sealed ionization chamber" and the case is fairly thick metal\nso I\'d believe that it would stop [not to energetic] alpha and beta\nradiation.\n\nExactly what did you have in mind that I could find on eBay that would be a\ndecent gamma emitter?\n\nNorm\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>"Liui Ganishiapu" <void@invalid.com> wrote in message
news:2kb97qFb4thU1@uni-berlin.de...
> You can buy some items from ebay to test with. If you are getting a click
or
> two per min, it is picking up background radiation, which means it is
> working good. Many meters back then were for post necular war, which means
> they only regester very high levels of radiation, which you don't want to
be
> around anyway. Do you have a make and model # on it?
>
It's a Victoreen Model 1A [also called a CD V-715] "designed to be used by
radiological Civil Defense personnel in determining radioactive
contamination levels that may result from an enemy attack or other nulear
disasters."
The range of sensitivity is roughly .03 to 500 roentgens per hour and is
supposed to be sensitive to only \gamma radiation. It contains a
"hermetically sealed ionization chamber" and the case is fairly thick metal
so I'd believe that it would stop [not to energetic] \alpha and \beta
radiation.
Exactly what did you have in mind that I could find on eBay that would be a
decent \gamma emitter?
Norm
Jim Adney
Jul2-04, 04:32 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nOn Tue, 29 Jun 2004 22:58:04 +0000 (UTC) Jon Elson\n<jmelson@artsci.wustl.edu> wrote:\n\n>I\'m guessing, from the description, that this is an ionization chamber,\n>not a Geiger-Muller tube detector.\n\nWhat\'s the difference between the two? I thought the G-M tube WAS an\nionization chamber.\n\n-\n-----------------------------------------------\nJim Adney jadney@vwtype3.org\nMadison, WI 53711 USA\n-----------------------------------------------\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Tue, 29 Jun 2004 22:58:04 +0000 (UTC) Jon Elson
<jmelson@artsci.wustl.edu> wrote:
>I'm guessing, from the description, that this is an ionization chamber,
>not a Geiger-Muller tube detector.
What's the difference between the two? I thought the G-M tube WAS an
ionization chamber.
-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
John McMillan
Jul2-04, 06:09 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n> It\'s a Victoreen Model 1A [also called a CD V-715] "designed to be used by\n> radiological Civil Defense personnel in determining radioactive\n> contamination levels that may result from an enemy attack or other nulear\n> disasters."\n>\n> The range of sensitivity is roughly .03 to 500 roentgens per hour and is\n> supposed to be sensitive to only gamma radiation. It contains a\n> "hermetically sealed ionization chamber" and the case is fairly thick metal\n> so I\'d believe that it would stop [not to energetic] alpha and beta\n> radiation.\n\nIf you search on Google you\'ll find pictures and details of that instrument.\nAs you say its based on an ionization chamber. I\'m guessing that the\nelectronics was some sort of electrometer circuit - it converts the\nionization in the chamber to a DC current displayed on the meter.\nSo, unlike the pulse processing used with a geiger tube, there\nwon\'t be any clicks to listen for.\n\n\n> Exactly what did you have in mind that I could find on eBay that would be a\n> decent gamma emitter?\n\nYour best choices for radioactive material to demonstrate that the\nunit is working are gas lamp mantles (Welsbach mantles) containing\nThorium and old luminous watches (or luminous instrument dials)\ncontaining radium. Then there are geological samples like pitchblende\n(uranium) and monazite (thorium). There are ceramics around with\nuranium in the glaze and thoria crucibles have been used for high\ntemperature stuff. Another approach is to take a domestic smoke\ndetector and extract the source from it. Its normally about\n40 kilobecquerels of Americium-241 which besides being an alpha\nemitter gives 60keV gammas. When handling this (or any other)\nsource, treat it with respect and above all avoid ingesting the\nmaterial.\nMy last suggestion for an easily available source is\na few hundred grams of "low-sodium" salt - which is mostly\npotassium chloride. All potassium salts contain Potassium-40\nwhich is a gamma emitter (1.4MeV). With a geiger, 200g "low sodium"\nclose to the tube doubles the background rate. However in your\ncase I suspect that the ionization chamber will not be sensitive enough to\ndetect it.\nHaving demonstrated that the unit works, you might still want\nto calibrate it. I can\'t imagine that it was ever particularly\naccurate - more a go/no-go device. Accurate calibration really\nwill require the resources of a decent radiological lab and this\nwill take time and effort.\n\nregards\n\nJohn McMillan\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>It's a Victoreen Model 1A [also called a CD V-715] "designed to be used by
> radiological Civil Defense personnel in determining radioactive
> contamination levels that may result from an enemy attack or other nulear
> disasters."
>
> The range of sensitivity is roughly .03 to 500 roentgens per hour and is
> supposed to be sensitive to only \gamma radiation. It contains a
> "hermetically sealed ionization chamber" and the case is fairly thick metal
> so I'd believe that it would stop [not to energetic] \alpha and \beta
> radiation.
If you search on Google you'll find pictures and details of that instrument.
As you say its based on an ionization chamber. I'm guessing that the
electronics was some sort of electrometer circuit - it converts the
ionization in the chamber to a DC current displayed on the meter.
So, unlike the pulse processing used with a geiger tube, there
won't be any clicks to listen for.
> Exactly what did you have in mind that I could find on eBay that would be a
> decent \gamma emitter?
Your best choices for radioactive material to demonstrate that the
unit is working are gas lamp mantles (Welsbach mantles) containing
Thorium and old luminous watches (or luminous instrument dials)
containing radium. Then there are geological samples like pitchblende
(uranium) and monazite (thorium). There are ceramics around with
uranium in the glaze and thoria crucibles have been used for high
temperature stuff. Another approach is to take a domestic smoke
detector and extract the source from it. Its normally about
40 kilobecquerels of Americium-241 which besides being an \alpha
emitter gives 60keV gammas. When handling this (or any other)
source, treat it with respect and above all avoid ingesting the
material.
My last suggestion for an easily available source is
a few hundred grams of "low-sodium" salt - which is mostly
potassium chloride. All potassium salts contain Potassium-40
which is a \gamma emitter (1.4MeV). With a geiger, 200g "low sodium"
close to the tube doubles the background rate. However in your
case I suspect that the ionization chamber will not be sensitive enough to
detect it.
Having demonstrated that the unit works, you might still want
to calibrate it. I can't imagine that it was ever particularly
accurate - more a go/no-go device. Accurate calibration really
will require the resources of a decent radiological lab and this
will take time and effort.
regards
John McMillan
Jon Elson
Jul4-04, 07:39 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nJim Adney wrote:\n> On Tue, 29 Jun 2004 22:58:04 +0000 (UTC) Jon Elson\n> <jmelson@artsci.wustl.edu> wrote:\n>\n>\n>>I\'m guessing, from the description, that this is an ionization chamber,\n>>not a Geiger-Muller tube detector.\n>\n>\n> What\'s the difference between the two? I thought the G-M tube WAS an\n> ionization chamber.\n\nWell, yes, ionization works in both. But, in a G-M tube, the high\nvoltage gradient causes an avalanche that drains the charge stored\non the capacitance of the tube and wiring until the discharge\nquenches, and the circuit resets. This causes a very large voltage\nspike which is easily detected, and you "count" the pulses to\nget dose rate. (Most G-M counters use some kind of gated integrator\nto convert the pulses to an analog voltage to be displayed on\na DeArsonval meter.)\n\nAn ionization chamber radiation meter does NOT work in the avalanche\nmode, but uses a very sensitive current sensing circuit (usually\nusing Victoreen electrometer tubes) to sense the current flowing\nacross a large gas-filled chamber and polarized with a very LOW\nelectric field. Instead of fields like 900 V/cm in the G-M tube,\nyou\'d see 20 V/10 cm in an ionization chamber. The ions drift slowly\nacross the chamber, and picoampere currents flow. The design of\nthe chamber and window often allow much lower particle energies to\nbe detected with an ion chamber. Also, extremely high dose rates\nwhich would saturate a GM tube can be accurately measured with\nan ion chamber. Of course, if you ever see these sorts of rates,\nyou\'d better run like hell!\n\nJon\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Jim Adney wrote:
> On Tue, 29 Jun 2004 22:58:04 +0000 (UTC) Jon Elson
> <jmelson@artsci.wustl.edu> wrote:
>
>
>>I'm guessing, from the description, that this is an ionization chamber,
>>not a Geiger-Muller tube detector.
>
>
> What's the difference between the two? I thought the G-M tube WAS an
> ionization chamber.
Well, yes, ionization works in both. But, in a G-M tube, the high
voltage gradient causes an avalanche that drains the charge stored
on the capacitance of the tube and wiring until the discharge
quenches, and the circuit resets. This causes a very large voltage
spike which is easily detected, and you "count" the pulses to
get dose rate. (Most G-M counters use some kind of gated integrator
to convert the pulses to an analog voltage to be displayed on
a DeArsonval meter.)
An ionization chamber radiation meter does NOT work in the avalanche
mode, but uses a very sensitive current sensing circuit (usually
using Victoreen electrometer tubes) to sense the current flowing
across a large gas-filled chamber and polarized with a very LOW
electric field. Instead of fields like 900 V/cm in the G-M tube,
you'd see 20 V/10 cm in an ionization chamber. The ions drift slowly
across the chamber, and picoampere currents flow. The design of
the chamber and window often allow much lower particle energies to
be detected with an ion chamber. Also, extremely high dose rates
which would saturate a GM tube can be accurately measured with
an ion chamber. Of course, if you ever see these sorts of rates,
you'd better run like hell!
Jon
Norm Dresner
Jul4-04, 07:40 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n"ping" <daniel_thorn@mac.com> wrote in message\nnews:17beea79.0406302147.4587876f@posting .google.com...\n>\n> The Roentgen (R) is a unit used to measure a quantity called exposure.\n> This can only be used to describe an amount of gamma and X-rays, and\n> only in air. One roentgen is equal to depositing in dry air enough\n> energy to cause 2.58E-4 coulombs per kg. It is a measure of the\n> ionizations of the molecules in a mass of air. The main advantage of\n> this unit is that it is easy to measure directly, but it is limited\n> because it is only for deposition in air, and only for gamma and x\n> rays.\n>\n\nWhat\'s the probability that X-Rays from a dentist\'s equipment would possess\nenough energy to register in the detector?\n\nNorm\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>"ping" <daniel_thorn@mac.com> wrote in message
news:17beea79.0406302147.4587876f@posting.google.c om...
>
> The Roentgen (R) is a unit used to measure a quantity called exposure.
> This can only be used to describe an amount of \gamma and X-rays, and
> only in air. One roentgen is equal to depositing in dry air enough
> energy to cause 2.58E-4 coulombs per kg. It is a measure of the
> ionizations of the molecules in a mass of air. The main advantage of
> this unit is that it is easy to measure directly, but it is limited
> because it is only for deposition in air, and only for \gamma and x
> rays.
>
What's the probability that X-Rays from a dentist's equipment would possess
enough energy to register in the detector?
Norm
Norm Dresner
Jul4-04, 07:40 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n"John McMillan" <j.e.mcmillan@nospam.sheffield.ac.uk> wrote in message\nnews:j.e.mcmillan-0207041156350001@dyn006187.shef.ac.uk...\n>\n>\n> > It\'s a Victoreen Model 1A [also called a CD V-715] "designed to be used\nby\n> > radiological Civil Defense personnel in determining radioactive\n> > contamination levels that may result from an enemy attack or other\nnulear\n> > disasters."\n> >\n> > The range of sensitivity is roughly .03 to 500 roentgens per hour and is\n> > supposed to be sensitive to only gamma radiation. It contains a\n> > "hermetically sealed ionization chamber" and the case is fairly thick\nmetal\n> > so I\'d believe that it would stop [not to energetic] alpha and beta\n> > radiation.\n>\n> If you search on Google you\'ll find pictures and details of that\ninstrument.\n> As you say its based on an ionization chamber. I\'m guessing that the\n> electronics was some sort of electrometer circuit - it converts the\n> ionization in the chamber to a DC current displayed on the meter.\n> So, unlike the pulse processing used with a geiger tube, there\n> won\'t be any clicks to listen for.\n>\n\nYes. The circuit contains exactly one transistor used as an oscillator to\ndrive the primary side of a transformer to get the voltages needed to run\nthe ionization chamber and the Ion Current Detector Tube (VX86 manufactured\nby Victoreen) which contains a cathode, an anode, and two grids. Based on\nthe resistors in the circuit (they range from 220 Megohms up to 220\ngigohms), we\'re talking about picoamperes of ionization current being\ndetected. The circuit itself is a marvel of economy. with just the two\nactive elemetns and three diodes along with the resistors and capacitors.\nI\'m going to try to find a luminous watch first and, failing that, use one\nof the two smoke detectors we have.\n\nThanks for the suggestions\nNorm\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>"John McMillan" <j.e.mcmillan@nospam.sheffield.ac.uk> wrote in message
news:j.e.mcmillan-0207041156350001@dyn006187.shef.ac.uk...
>
>
> > It's a Victoreen Model 1A [also called a CD V-715] "designed to be used
by
> > radiological Civil Defense personnel in determining radioactive
> > contamination levels that may result from an enemy attack or other
nulear
> > disasters."
> >
> > The range of sensitivity is roughly .03 to 500 roentgens per hour and is
> > supposed to be sensitive to only \gamma radiation. It contains a
> > "hermetically sealed ionization chamber" and the case is fairly thick
metal
> > so I'd believe that it would stop [not to energetic] \alpha and \beta
> > radiation.
>
> If you search on Google you'll find pictures and details of that
instrument.
> As you say its based on an ionization chamber. I'm guessing that the
> electronics was some sort of electrometer circuit - it converts the
> ionization in the chamber to a DC current displayed on the meter.
> So, unlike the pulse processing used with a geiger tube, there
> won't be any clicks to listen for.
>
Yes. The circuit contains exactly one transistor used as an oscillator to
drive the primary side of a transformer to get the voltages needed to run
the ionization chamber and the Ion Current Detector Tube (VX86 manufactured
by Victoreen) which contains a cathode, an anode, and two grids. Based on
the resistors in the circuit (they range from 220 Megohms up to 220
gigohms), we're talking about picoamperes of ionization current being
detected. The circuit itself is a marvel of economy. with just the two
active elemetns and three diodes along with the resistors and capacitors.
I'm going to try to find a luminous watch first and, failing that, use one
of the two smoke detectors we have.
Thanks for the suggestions
Norm
David Williams
Jul6-04, 01:47 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n-> What\'s the probability that X-Rays from a dentist\'s equipment would possess\n-> enough energy to register in the detector?\n\n-> Norm\n\nZero, I suspect.\n\nBut many hospitals have machines to do radiotherapy on cancer patients\nwhich contain Cobalt-60, which emits gamma rays. These should\n*certainly* show on the detector.\n\ndow\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>-> What's the probability that X-Rays from a dentist's equipment would possess
-> enough energy to register in the detector?
-> Norm
Zero, I suspect.
But many hospitals have machines to do radiotherapy on cancer patients
which contain Cobalt-60, which emits \gamma rays. These should
*certainly* show on the detector.
dow
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nNorm Dresner:\n>\n>"ping" <daniel_thorn@mac.com> wrote in message\n>news:17beea79.0406302147.4587876f@postin g.google.com...\n>>\n>> The Roentgen (R) is a unit used to measure a quantity called exposure.\n>> This can only be used to describe an amount of gamma and X-rays, and\n>> only in air. One roentgen is equal to depositing in dry air enough\n>> energy to cause 2.58E-4 coulombs per kg. It is a measure of the\n>> ionizations of the molecules in a mass of air. The main advantage of\n>> this unit is that it is easy to measure directly, but it is limited\n>> because it is only for deposition in air, and only for gamma and x\n>> rays.\n>>\n>\n>What\'s the probability that X-Rays from a dentist\'s equipment would possess\n>enough energy to register in the detector?\n\nDepends upon what the counter was originally designed to count. If\nthe window is thin enough, x-rays should be fine, unless you want to\ncheck the calibration rather than just find out if it detects gammas.\nThe best way to find out is try it. If it doesn\'t respond, then either\nit doesn\'t or the window is too thick, in which case, you\'ll have to\nfind a higher energy source. If you have a smoke detector which\nuses 241Am, that will also provide a source low energy (approx 50 keV)\nX-rays. (Your counter won\'t see any of the alpha\'s from the 241Am).\n\nYou might also try to find a physician or veterinarian who does\nradiation therapy. These days, even veterinarians have linacs and\nuse radionuclides for treating cancers in animals. Decay energies\nfor those isotopes will be nominally in the MeV range. If your counter\ndoesn\'t see those, it doesn\'t work.\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Norm Dresner:
>
>"ping" <daniel_thorn@mac.com> wrote in message
>news:17beea79.0406302147.4587876f@posting.google.c om...
>>
>> The Roentgen (R) is a unit used to measure a quantity called exposure.
>> This can only be used to describe an amount of \gamma and X-rays, and
>> only in air. One roentgen is equal to depositing in dry air enough
>> energy to cause 2.58E-4 coulombs per kg. It is a measure of the
>> ionizations of the molecules in a mass of air. The main advantage of
>> this unit is that it is easy to measure directly, but it is limited
>> because it is only for deposition in air, and only for \gamma and x
>> rays.
>>
>
>What's the probability that X-Rays from a dentist's equipment would possess
>enough energy to register in the detector?
Depends upon what the counter was originally designed to count. If
the window is thin enough, x-rays should be fine, unless you want to
check the calibration rather than just find out if it detects gammas.
The best way to find out is try it. If it doesn't respond, then either
it doesn't or the window is too thick, in which case, you'll have to
find a higher energy source. If you have a smoke detector which
uses 241Am, that will also provide a source low energy (approx 50 keV)
X-rays. (Your counter won't see any of the \alpha's from the 241Am).
You might also try to find a physician or veterinarian who does
radiation therapy. These days, even veterinarians have linacs and
use radionuclides for treating cancers in animals. Decay energies
for those isotopes will be nominally in the MeV range. If your counter
doesn't see those, it doesn't work.
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