health effects

[Rajini]

Hello all,
i need one suggestion for shielding of a gamma source.
I have a gamma source with initial activity of 50 mCi=1.85X10^9Bq.
What thickness of lead needed to protect myself!
I used the formula I(x)=I exp(-kx). I=50mCi; k=37.6 cm^2/g (linear attenuation for 122 keV) and x the thickness needed (i took I(x)=1). By the above formula i get ~6mm. Is that okay..
if i am wrong pls. correct me!
2. Is there any good website to get k (linear attenuation) values???

thanks

[Astronuc]

Um - what radioisotope?

I would presume one has this material in a controlled environment in a laboratory or licensed facility?! And why would one need to be asking about shielding?

[Rajini]

57Co-isotope (details are there on www; but about shielding?) for mössbauer spectroscopy! (i am working with it, but i am not sure about shielding)
thanks

[Astronuc]

Are you doing the mössbauer spectroscopy in a laboratory? If so, I would expect that someone from the health physics department would have set up the shielding. Also, such sources would come in a shielded (shipping/storage) container, such that at the surface, the dosage should be about background, or no more than an order of magnitude above background.

[Rajini]

Hello..
Yes...but here some ppl. from (tüv)+health guys checked..they said its okay..but i am worried..because in other labs i noticed they use around 5 cm. That why i asked here...
actually are not big mössbauer gurus..so ppl. pay less attention..
thanks
..i already mounted the source..i used a lead glass..equivalent to 3 mm lead..(however my hands are exposed..for some seconds)
i think 6 mm should be fine..any we dont stay there for more than a minute per day..sometimes..per week

[Astronuc]

Normally a gamma source would be in a shielded container. In Mössbauer spectroscopy, the source should be shielded and collimated.

TÜV personnel are normally very conscientious. If you have concerns, then talk to the supervisor about your concerns and perhaps request additional shielding. I presume one has a dosimeter badge since one is working around radioactive sources. If not - one should immediately get one and become registered with the radiation protection group at the lab.

[Rajini]

Oh yes..we did that!...(one more time)..
They actually did based on strength, lead thickness and also on exposion dose rate.
and i am completely safe!
thanks