Task Group 2 Iris Abt Michael Altmann Kevin

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

Prototype Test-stands & Crystals 2 Canberra crystals (n-type) ØMikesch-I : non-segment ØMikesch-II: 18 segments, 6 x 3 z (end of year) 3 DSG crystals (p-type) ØRoland-I : true coaxial, non-segment ØRoland-II : 6 segments ØRoland-III: 18 segments, 6 x 3 z (end of year) Gerda Collab. , Nov. 9 -11, 2005 3 test-stands: üMilchkanne: LN 2 üGerdalinchen: LN 2 üGalatea: Vacuum Page 2

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

Mikesch in LN 2 13 LN 2 & 1 LAr cooling-warming cycles FWHM~3. 5 ke. V (electronic noise dominated) Rise-time vs. crystal angle (241 Am) Crystal axis affects electron-hole drift velocity Gerda Collab. , Nov. 9 -11, 2005 Page 4

Mikesch in LAr In LN 2 Eu 152 spectrum Gerda Collab. , Nov. 9 -11, 2005 Page 5

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

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

DSG Roland-I & II performance Roland-I leakage current Roland-II A Roland-II Current (2 k. V) No shield 8. 4 n. A Shield – 120°C 120 p. A Shield in LN 2 55 p. A V_bias Infrared increases leakage current, shielding very important Gerda Collab. , Nov. 9 -11, 2005 Page 8

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

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

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

Ma. Ge simulation results ( ) ( , ) Gerda Collab. , Nov. 9 -11, 2005 Page 12

Ma. Ge simulation results Dominant backgrounds: ü 68 Ge in crystals ü 238 U, 232 Th in crystals <0. 4 Bq/kg ü 210 Pb on crystal surface <0. 2 Bq/kg ü 238 U, 232 Th in Kapton cable <2 m. Bq/kg ü 238 U, 232 Th in junction box <0. 5 m. Bq/kg Upper limit on other materials: material 238 U (m. Bq/kg) 232 Th (m. Bq/kg) Cu (holder) 0. 4 0. 2 Cu (string) 10 10 Teflon (holder) 1. 9 1. 4 Gerda internal note (GSTR-05 -019) ready Gerda Collab. , Nov. 9 -11, 2005 Page 13

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

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

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

Backup: Co 60, Ge 68, Pb 210 contamination Co 60 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 Ge 68 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 Pb 210 on surface: 4000 Rn/crystal during installation 45 decays/year/crystal 0. 26 Bq/kg Gerda Collab. , Nov. 9 -11, 2005 Page 17

Ma. Ge simulation Components: ü Crystal ü Cu holder ü Teflon holder ü Cu suspension string ü kapton cable ü bonding pads ü electronic Junction box Gerda Collab. , Nov. 9 -11, 2005 Contaminations: üTh 232 üU 238 üPb 210 üCo 60 üGe 68 Page 18

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

Materials & Ma. Ge MC Cu: ü Cresst, Gerda, Majorana ü Majorana Cu stress test: ok for 35 kg Kapton-cable: ü pure K, K-Cu-Ni-Au ü contamination measurement in HADES Ma. Ge simulation üHolder üSuspension string üKapton cable üJunction box ücrystals Need MC for contamination limit Gerda Collab. , Nov. 9 -11, 2005 Page 20

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

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