why cosmic ray intensity needs correction with pressure?


by sctheorist
Tags: correction, cosmic, intensity, pressure
sctheorist
sctheorist is offline
#1
Nov25-12, 01:02 PM
P: 4
Hi guys,
I cannot understand why we need to correct cosray intensity with pressure and why the equation that describes the phenomenon is I=Io*exp(-a(Δp))? I want to know the phsyical meaning of this(i assume,experimental) result...

Thank you...
Phys.Org News Partner Physics news on Phys.org
Better thermal-imaging lens from waste sulfur
Scientists observe quantum superconductor-metal transition and superconducting glass
New technique detects microscopic diabetes-related eye damage
mfb
mfb is offline
#2
Nov25-12, 02:17 PM
Mentor
P: 10,798
More context would help.
A correction where, and depending on which pressure?
sctheorist
sctheorist is offline
#3
Nov25-12, 02:44 PM
P: 4
By pressure I mean the atmospheric pressure above the neutron monitor for example..The exact equation is:

I=Io*exp(-a(Pi-Pm)) where:

I=corrected with pressure intensity of cosray
Io=the intensity recorded by the neutron monitor
a= constant(namely the pressure coefficient)
Pi=the atm. pressure at the time of measurment
Po=the mean value of pressure in a particular amplitude where the measurment is taken

thanks...

Vanadium 50
Vanadium 50 is offline
#4
Nov25-12, 03:59 PM
Mentor
Vanadium 50's Avatar
P: 15,576

why cosmic ray intensity needs correction with pressure?


The higher the pressure, the more material (air) is above you and the fewer cosmic rays get through.
sctheorist
sctheorist is offline
#5
Nov25-12, 06:11 PM
P: 4
Look Vanadium 50,

if the pressure is Pi>Pm then the argument in the exp is negative(a is positive) and exp(-a(Pi-Pm) is less than 1.So the corrected value I is less than the recorded Io,which doesn't make sense. In high pressure you supposed to record a value i.e. Io=40 and the correction should be I>Io because high pressure prevents you to count all events available,right?That's a contadiction if I am not wrong...
Vanadium 50
Vanadium 50 is offline
#6
Nov25-12, 07:34 PM
Mentor
Vanadium 50's Avatar
P: 15,576
Look, sctheorist (why so rude?) the sign of the correction depends on the sign of a.
sctheorist
sctheorist is offline
#7
Nov26-12, 10:55 AM
P: 4
No no you misunderstood my friend...I used "look"' in a friendly manner..Maybe it's because I'm not american..Seriously I didn't mean to offend you or something..In my language this phrase has a different meaning..Anyway...

I had a thought today about that..Maybe it has something to do with the equation I=Io*exp(-μχ) that refers to an absorber above your detector. χ being the length of the path within the absorber that the particle crosses..
mfb
mfb is offline
#8
Nov26-12, 11:01 AM
Mentor
P: 10,798
Maybe it is just the interpretation of the parameters:
Quote Quote by sctheorist View Post
By pressure I mean the atmospheric pressure above the neutron monitor for example..The exact equation is:

I=Io*exp(-a(Pi-Pm)) where:

I=corrected with pressure intensity of cosray
Io=the intensity recorded by the neutron monitor
a= constant(namely the pressure coefficient)
Pi=the atm. pressure at the time of measurment
Po=the mean value of pressure in a particular amplitude where the measurment is taken

thanks...
If I0 corresponds to Pm (I think this should be P0) and I corresponds to Pi and a is positive:
Pi-Pm>0 (more pressure at i) corresponds to I<I0 (lower neutron flux at i).


Register to reply

Related Discussions
Thermometer stem correction with pressure Introductory Physics Homework 1
Pressure Amplitude and Decreasing Intensity Classical Physics 4
Sound intensity with pressure amplitude and temperature? Introductory Physics Homework 0
Fluid Mechanics Pressure Intensity Diagrams General Engineering 3
Wave Derivation: Intensity and Pressure Amplitude Relationship Introductory Physics Homework 0