Progress of TG-1 activities (refurbishment of Phase-I detectors) Stefan Schönert on behalf of TG 1 GERDA general meeting Tuebingen, Nov. 9-11, 2005

Outline Detector laboratory at LNGS (LArGe) Transportation of IGEX detectors to GS Refurbishment –detector support and contacts –mechanical/thermal prototype –non-enriched prototype diode –recovery strategy –overall refurbishment and testing strategy Summary / outlook

Underground detector lab (LArGe) ‘Rn-free’ clean bench (detector mounting) ‘Rn-free’ detector test stand: electro-polished dewar & HP-LN refill system (not shown)

Ongoing work to get underground detector lab operational Installation of ‘Rn-free’ clean bench and detector test stand Start-up of chemistry equipment (DI-water, acids, alcohol): purification of Cu & PTFE, methanol wash of Ge-diode transformation into clean room Completion: early December

Transportation of IGEX detectors Transport box sent by Frank Avignone to Canfranc Nov. 13: Igor, Andrey & Peter  Canfranc Nov. 15/16: preparation and packing of detectors with help of Zaragoza group Nov. 17: sprinter (accompanied by Andrey) Canfranc  GS; above ground < 24h Testing of detectors at GS by Andrey & Igor and Oleg Thanks to Julio Morales and Frank Avignone for support! IGEX super-boxes (3x)

Detector refurbishment: support, contacts & array geometry Single detectorPhase-I detector array Design review of contacts and support with Canberra, Olen Prototypes Cooperation during refurbishment (if needed) worked out All materials procured PTFE and Cu screened

Detector refurbishment: mechanical and thermal prototype Silicon spring for inner contact Signal feed through Result of LN cooling test: replacement of one PTFE part by Si

Detector refurbishment: destruction test: verification of safety factor Deformation as expected Safety factor 3 experimentally confirmed Material strength increases at LN temperature Finite element calc. Destructive test

Cleaning of copper parts Electro polished (same procedure as GeMPI detector parts) Chemically etched 1% H 2 SO 4 + 3% H 2 O 2 5 min 1% citric acid5 min Possible sequence (to be finalized): 1) electro-polishing 2) chemical etching (underground) 100  m Surface of copper after machining (electro-erosion)

non-enriched prototype diode Goal: test contacts & support of system Prototype for enriched detector if refurbished at Canberra (Chinese hat) 2 kg diode ready for mounting and testing at Olen Detector support and contacts in workshop Mounting and testing in November/December

Transport and storage container Clean storage of diodes after dismounting and after testing Electro-polished stainless steal container Selected Butyl O- rings (low Rn emanation)

Recovery strategy Possible failure modes and strategies for recovery worked out with Canberra, Olen In synthesis: Dismounting and re-contacting underground at GS w/o modification of diode In case of failure (e.g. damage of Ge-oxide passivation layer, boron implantation) refurbishment at Canberra (Olen) with underground storage in Hades. –Maximize probability to get working diode –Minimize exposure time (~ 1 week) at the prize of moderate material loss (~ 100 g)  Change of Ortec type contacts to Canberra type with groove  Canberra type of passivation

Refurbishment and testing strategy Underground refurbishment Test in LN stand Refurbish. at Olen Underground storage Operation Big tank (physics run) yes no fast Underground refurbishment Test in LN stand Refurbish. at Olen Underground storage Bgd. testing In LArGe physics? Operation Big tank (physics run) yes no delayed Underground refurbishment Test in LN stand Refurbish. at Olen Underground storage Bgd. testing In LArGe Operation Big tank (physics run) yes no on timeGERDA: no yes

Summary / Outlook Nov: transportation of IGEX detectors to GS Nov: startup of underground detector laboratory (LArGe barrack) Nov: test non-enriched prototype in LN at Canberra Olen Dec: dismount 1 st enriched diode (verify dimensions) – to be confirmed with Russian partners Production of low-background support Jan: start-up of LN setup at LNGS and operation of prototype Subsequent: test of enriched diode in LN at GS