tg 11 overview - material screening - hardy simgen mpi für kernphysik heidelberg
Post on 19-Dec-2015
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Outline
Gamma-ray screening Radon:
Online monitoring Behaviour of Rn and Rn daughters Emanation measurements
Hardware: New gas counting system at LNGS New Germanium spectrometer for MPIK
Gamma-ray screening resultsActivities in [mBq/kg]
Sample 226Ra 228Th 228Ra 40KSticky tape (TESA) <60 <140 <100 <440
Mineral oil 6 2 9 2 <15 44 20
Silicone gel <40 <6 <12 60 36
Polyurethane (black)
6500 400
3900 4004200
40026500
3400
PMT cable 180 30 <130 <160 560 230
Iglidur granulate Drylin
<6.5 <4.6 <15 130 10
Foamable polystyrene
0.48 0.06
0.38 0.070.48 0.10
3.6 0.7
Graphite1700
2002300 300
2000 300
2700 900
Behaviour of radon + radon daughters
Work is proceeding in Cracow No update this time, but:
„We are getting a clearer picture of Rn + Rn daughters in LN2, but it is not yet complete“ (Marcin Wojcik).
Further activity in preparation:
Behaviour of Rn daughters on Ge discs
Ability to measure gaseous radioactive isotopes at Gran Sasso (222Rn, 85Kr, 37Ar, 39Ar, 133Xe, 71Ge, ... ).
On-site 222Rn emanation measurements are now possible for small samples.
sample250
damping-plate
PMT 1“x1“
≈ 2015 mm
Airlock like GeMPI 2 and 3
sample
Airtight glovebox system
Plasticscintillator 2 plates 30 mm each
Cu 50 mm
Plasticsc50 mm
Pb 50 mm and more
PE + BC450 mm
Cu-frame for block
(existing) steel frame529x529x750?
Item- profil
≈ 1250 mm
steel plate
≈ 1300
Ge
sample
sample
sample
airlock
View from top sample-chamber
openmiddle veto counter
slided aside
shielding-block lifted up and slides aside
sample container are moved along rails
Airtight glovebox system
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30
Time after complete 228Ra removal [y]
Rel
ativ
e to
232 T
h ac
tivi
ty
228 Th
228 Ra
228Th activity
228Ra activity
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
0 5 10 15 20 25 30
t [a]
A22
8 /
A23
2
228 Th
228 Ra
time since Ra removal [y]rel. a
ctiv
ity a
fter
Ra
rem
oval
rel. a
ctiv
ity a
fter
Ra
rem
oval
time since Ra removal [y]
Disequilibrium in the Th decay chain
From: A focused review of operations and thorium exposures at the Dow Chemical Company Madison Plant, Advisory Board on Radiation and Worker Health (S. Cohen and Associates,2007)
G. H. GERDA collab. Meeting, Padova 11. -13. March 09