TG 11 overview- Material screening -

Hardy Simgen

MPI für Kernphysik Heidelberg

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

Gamma-ray screening

Screening of PCB for PZ0 Matthias Laubenstein‘s talk

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

Radon monitor

Ready for shipping Jochen Schreiner‘s talk

222Rn emanation measurements

Focus on cryostat and lock Grzegorz Zuzel‘s talk

GNO shield for proportional counters

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

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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

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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

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 activityG5

G7

∞

exposure age via 54Mn

time since Ra removal [y]

rel. a

ctiv

ity a

fter

Ra r

em

oval

G. H. GERDA collab. Meeting, Padova 11. -13. March 09