Progress of TG-1 activities(refurbishment of Phase-I detectors)

Stefan Schönerton behalf of TG 1

GERDA general meetingTuebingen, 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 detector Phase-I detector array

•Design review of contactsand 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% H2SO4 + 3% H2O2 5 min

1% citric acid 5 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 grooveCanberra type of passivation

Refurbishment and testing strategy

Underground refurbishment

Test in LNstand

Refurbish.at Olen

Underground storage

Operation Big tank

(physics run)

yes

no

fast

Underground refurbishment

Test in LNstand

Refurbish.at Olen

Underground storage

Bgd. testing In LArGe physics?

Operation Big tank

(physics run)

yes

no

delayed

Underground refurbishment

Test in LNstand

Refurbish.at Olen

Underground storage

Bgd. testing In LArGe

Operation Big tank

(physics run)

yes

no

on timeGERDA:

noyes

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 1st 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