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Majarana double beta decay program. Overview: Phased approach and scientific reach Funding and schedule Experimental layout and detailed infrastructure needs Change in strategy and schedule given LAr option. Peter Doe, on behalf of the Majorana collaboration.

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slide1

Majarana double beta decay program

  • Overview:
    • Phased approach and scientific reach
    • Funding and schedule
    • Experimental layout and detailed infrastructure needs
    • Change in strategy and schedule given LAr option

Peter Doe, on behalf of the Majorana collaboration

SNOLab-Majarana Aug. ‘05

slide2

Phased approach and scientific reach

  • Scalable  3 phases:

M180… 180 kg, 86% enriched 76Ge,

60 kg 120 kg 180 kg “conventional” technology

m≥ 120 meV (degenerate hierarchy)

M500/M1000…500-1000 kg,

LAr/LN2 collaboration with GERDA?

m≥ 50 meV (inverted hierarchy)

MX000… Technology unknown?

m≥ 10 meV (normal hierarchy)

SNOLab-Majarana Aug. ‘05

slide3

Possibility of early activity U/G in FY-06

Funding from Majorana institutional support

No federal funding before FY-07

Funding

Expect NuSAG response at end of August

?

SNOLab-Majarana Aug. ‘05

slide4

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

R&D Module

Construction

Enriched

Ge

1st 60 kg

running

2nd 60 kg

running

3rd 60 kg

running

M180 Operating Phase

Schedule

SNOLab-Majarana Aug. ‘05

slide5
57 crystal module (60 kg)

Conventional vacuum cryostat made with electroformed Cu.

Three-crystal stack are individually removable.

Vacuum jacket

Cap

Cold Plate

Tube

(0.007” wall)

Cold Finger

Ge

(62mm x 70 mm)

1.1 kg Crystal

Tray

(Plastic, Si, etc)

Thermal

Shroud

Bottom Closure

1 of 19 crystal stacks

Majorana modular approach

SNOLab-Majarana Aug. ‘05

slide6
Allows modular deployment, early operation

contains up to eight 57-crystal modules (M180 populates 3 of the 8 modules)

four independent, sliding units

40 cm bulk Pb, 10 cm ultra-low background shield

active 4 veto detector

Veto Shield

Sliding Monolith

LN Dewar

Inner Shield

57 Detector Module

Majorana shield - conceptual design

Top view

SNOLab-Majarana Aug. ‘05

slide7

Experimental layout/infrastructure - M180

  • Three areas of underground activity:
    • Fabrication

Electroforming copper parts

    • Assembly

Putting it together

Making it work

    • Data taking - staged by module

60 kg 

120 kg 

180 kg

SNOLab-Majarana Aug. ‘05

slide8

Layout - Fabrication areas

Dimensions in meters

SNOLab-Majarana Aug. ‘05

slide9

Layout - Detector area

Dimensions in meters

SNOLab-Majarana Aug. ‘05

slide10

Low background electroformed copper

Electroformed cold finger and signal wires for MEGA

Mass, M180 copper

components

2 crystal thermal shroud, 250 mm wall thickness

SNOLab-Majarana Aug. ‘05

slide11

Electroforming copper - key elements

Electroforming copper

C

C

A

A

B

B

CuSO4

  • Semiconductor-grade acids
  • Copper sulfate purified by recrystallization
  • Baths circulated with continuous microfiltration to remove oxides and precipitates
  • Continuous barium scavenge removes radium
  • Cover gas in plating tanks reduces oxide formation
  • Periodic surface machining during production minimizes dendritic growth
  • H2O2 cleaning, citric acid passivation

232Th<8Bq/kg

Current density ~ 40mA/cm2

Plating rate ~ 0.05 mm/hr

SNOLab-Majarana Aug. ‘05

slide12

Electroforming copper - Infrastructure

  • HEPA-filtered air supply
  • Radon-scrubbed air for lowest-level work
  • Fume extractor for etching
  • Flammable and hazardous gas sensors
  • Radon-proof storage lockers with purge gas and vacuum capability
  • Etching and acid storage
  • Spill containment lining
  • Milli-Q water system w/DI supply water
  • Air-lock entry, washable walls
  • Air-conditioning to ~ 20 C
  • 10-6 Torr dry vacuum system

Cold plate for the MEGA feasibility study at WIPP, NM.

SNOLab-Majarana Aug. ‘05

slide13

Infrastructure (continued)

SNOLab-Majarana Aug. ‘05

slide14

M180 - Special considerations

  • Cryogens (1000 liters)
  • Waste gasses (electroforming, etching)
  • Acids (electroforming)
  • Solvents (alcohol, acetone…)
  • Oxidizers (dilute H2O2 cleaner)
  • Lead (shielding)
  • Flammable plastics (veto)
  • Compressed gasses
  • Radon-free inert cover gasses (LN2?)
  • Radioactive sources

SNOLab-Majarana Aug. ‘05

slide15

LAr option - strategy change and schedule

Decision

  • 2 year LArGe R&D 
      • Crystal, light stability in Lar
      • Detector Monte Carlo studies
      • Detector design
      • Engineering design
  • Estimate 3m Ø cryogenic vessel (~20 ton LAr)
  • Requires underground fabrication of dewar ( schedule)
  • Less electroformed copper parts ( schedule)
  • Would not change enrichment schedule
  • Would not change staging plan (~60120180 kg)
  • Would need higher overhead clearance (≥8 m ?)

SNOLab-Majarana Aug. ‘05

slide16

Summary

  • Majorana is modular, 60120180 500X,000 kg
  • M180 employs demonstrated, “conventional” technology
  • Material purity is critical, but achievable
  • Significant underground fabrication, assembly
  • Optimistically, enrichment late 2007, first data 2009/10
  • LAr option being investigated, little schedule impact(?)

SNOLab-Majarana Aug. ‘05

slide18

Electroforming numbers

Bath size:

Cryostat 40 cm high x 40 cm 

Tank 50cm x 75cm x 50cm 225 liters

x 8 tanks 1800 liters

Plating time:

Cryostat 3mm / 0.05 mm hr-1 = 60 hr

@50% efficiency, 12 hr/day = 10 days (2 weeks)

Bath power:

Cryostat Area =  x 202 x 40 = 5030 cm2

power = 5030 cm2 x 40 mA cm-2 2 kA

Assume 4 kW/bath  32 kW total

SNOLab-Majarana Aug. ‘05

slide19

Cu parts count

54 bath weeks, 100% contingency, 8 baths

 4 months electroforming @ 2 shifts/day, 5 days/week

SNOLab-Majarana Aug. ‘05

slide20

Plating Bath Process Parameters

  • Plating is done onto polished, cleaned, stainless steel mandrels in the shape of the desired parts
  • Current density is ~40 mA/cm2
  • Plating rate is ~0.05 mm/h
  • BaSO4 collects in the micro-filtration stage and acts as radium scavenge
  • CoSO4 was added as a holdback carrier for the cosmogenic 56,57,58,60Co present in the starting copper
  • HCl and Thiourea affect copper crystal nucleation and grain size

SNOLab-Majarana Aug. ‘05