1. Task Group 2 Iris Abt, Michael Altmann, Kevin Kroeninger, Bela Majorovits, Franz Stelzer, Xiang Liu 1.Detector Development 2.Suspension & Cabling 3.MC Simulation 4.Outlook & Conclusion

2. Prototype Test-stands & Crystals Gerda Collab., Nov. 9-11, 2005Page 2 3 test-stands: Milchkanne: LN2 Gerdalinchen: LN2 Galatea: Vacuum 2 Canberra crystals (n-type)  Mikesch-I : non-segment  Mikesch-II: 18 segments, 6  x 3z (end of year) 3 DSG crystals (p-type)  Roland-I : true coaxial, non-segment  Roland-II : 6  segments  Roland-III: 18 segments, 6  x 3z (end of year)

3. Gerda Collab., Nov. 9-11, 2005Page 3 Mikesch-I Eurysis Canberra n-type crystal Non segment Non-true-coaxial 1 st : Milchkanne & Mikesch crystal

4. Mikesch in LN 2 Gerda Collab., Nov. 9-11, 2005Page 4 13 LN2 & 1 LAr cooling-warming cycles FWHM~3.5keV (electronic noise dominated) Crystal axis affects electron-hole drift velocity Rise-time vs. crystal angle ( 241 Am)

5. Mikesch in LAr Gerda Collab., Nov. 9-11, 2005Page 5 In LAr In LN 2 Eu152 spectrum

6. 2 nd : Gerdalinchen & DSG Roland-I II Gerda Collab., Nov. 9-11, 2005Page 6 Similar to Gerda setup & environment Multi-purpose, test suspension strings Multi-crystals. IR shielding

7. 2 nd : Gerdalinchen & DSG Roland-I II Gerda Collab., Nov. 9-11, 2005Page 7 Roland-I Roland-II IR Shield

8. DSG Roland-I & II performance Gerda Collab., Nov. 9-11, 2005Page 8 Infrared increases leakage current, shielding very important Roland-I leakage current A Roland-II Current (2kV) No shield8.4nA Shield –120°C120pA Shield in LN255pA V_bias

9. Suspension system design Gerda Collab., Nov. 9-11, 2005Page 9 Kapton cable suspension string (Cu) holders (cu, teflon) bond pads

10. Cabling tests with optical crystal Gerda Collab., Nov. 9-11, 2005Page 10

11. Materials & MaGe MC Gerda Collab., Nov. 9-11, 2005Page 11 Cu: Cresst, Gerda, Majorana Majorana Cu stress test: ok for 35kg Kapton-cable: pure K, K-Cu, K-Cu-Ni-Au contamination measurement in HADES Need MC for contamination limit MaGe simulation

12. MaGe simulation results Gerda Collab., Nov. 9-11, 2005Page 12 ()() (,)(,)

13. MaGe simulation results Gerda Collab., Nov. 9-11, 2005Page 13 68 Ge in crystals 238 U, 232 Th in crystals <0.4  Bq/kg 210 Pb on crystal surface <0.2  Bq/kg 238 U, 232 Th in Kapton cable <2 mBq/kg 238 U, 232 Th in junction box <0.5mBq/kg Dominant backgrounds: Upper limit on other materials: material238U (mBq/kg)232Th (mBq/kg) Cu (holder)0.40.2 Cu (string)10 Teflon (holder)1.91.4 Gerda internal note (GSTR-05-019) ready

14. 3 rd Test-stand: Galatea Gerda Collab., Nov. 9-11, 2005Page 14 for laser,  &  sources inside Vacuum tank 3 stages for source

15. Outlook Gerda Collab., Nov. 9-11, 2005Page 15 Milchkanne Test-stand: More cycles, more lAr test Gerdalinchen Test-stand: Mikesch-II, Roland-I & II & III: resolution, mirror charge, pulse shape, crystal axis Galatea Vacuum Test-stand: with laser,  &  sources. all of the above, plus thickness of dead layers

16. Conclusion Gerda Collab., Nov. 9-11, 2005Page 16 Learned from test-stands: Crystals sensitive to IR radiation (both n,p-types) Need axis orientation of each crystal (for pulse shape) Crystals fragile with water Learned from MC: Dominant internal background sources located (68Ge in crystal, 238U 232Th in Kapton) Upper limit for all suspension and cabling materials. Complete prototype design of support & cable for Phase-II available.

17. Backup: Co60, Ge68, Pb210 contamination Gerda Collab., Nov. 9-11, 2005Page 17 Co60 in crystal: 4/kg/day above ground, assume 10 days above ground, 40 atoms/kg first year, 4.9 decays per kg,  0.16  Bq/kg Ge68 in crystal: 1/kg day, saturation 400 /kg assume 180 days from enriching to storage undergd., 145/kg 60% decay in first year,  2.7  Bq/kg Pb210 on surface: 4000 Rn/crystal during installation 45 decays/year/crystal  0.26  Bq/kg

18. MaGe simulation Gerda Collab., Nov. 9-11, 2005Page 18 Components: Crystal Cu holder Teflon holder Cu suspension string kapton cable bonding pads electronic Junction box Contaminations: Th232 U238 Pb210 Co60 Ge68

19. Crystal axis effect Gerda Collab., Nov. 9-11, 2005Page 19 Rege

20. Materials & MaGe MC Gerda Collab., Nov. 9-11, 2005Page 20 Cu: Cresst, Gerda, Majorana Majorana Cu stress test: ok for 35kg Kapton-cable: pure K, K-Cu, K-Cu-Ni-Au contamination measurement in HADES Need MC for contamination limit MaGe simulation Holder Suspension string Kapton cable Junction box crystals

21. Mikesch in LAr Gerda Collab., Nov. 9-11, 2005Page 5 In LAr In LN2

22. Roland-I pulse shapes & resolution Gerda Collab., Nov. 9-11, 2005Page 21 ns ss