The Majorana Collaboration

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The Majorana Collaboration
Brown University, Providence, RI Rick Gaitskell
Duke University, Durham, NC Werner
Tornow Institute for Theoretical and
Experimental Physics, Moscow, RussiaA. Barabash,
S. Konovalov, V. Stekhanov, V. Umatov Joint
Institute for Nuclear Research, Dubna, RussiaV.
Brudanin, S. Egorov, O. Kochetov, V. Sandukovsky
Lawrence Berkley National Laboratory, Berkley,
CAPaul Fallon, I. Y. Lee Lawrence Livermore
National Laboratory, Livermore, CAKai Vetter
Los Alamos National Laboratory, Los Alamos,
NMSteve Elliott, Andrew Hime New Mexico State
University, Carlsbad, NMJoel Webb
North Carolina State University, Raleigh, NC Eric
Adles, Rakesh Kumar Jain, Jeremy Kephart, Ryan
Rohm, Albert Young Pacific Northwest National
Laboratory, Richland, WAHarry Miley,
Co-spokesperson Craig Aalseth, Dale Anderson,
Ronald Brodzinski, Shelece Easterday, David
Jordan, Richard Kouzes, William Pitts, Robert
Thompson, Ray Warner University of Chicago,
Chicago, ILJuan Collar Osaka University, Osaka,
Japan Hiro Ejiri, Ryuta Hazama, Masaharu Nomachi
University of South Carolina, Columbia, SCFrank
Avignone, Co-spokesperson Horacio Farach, John
M. Palms, George King University of Washington,
Seattle, WA Peter Doe, Kareem Kazkaz, Hamish
Robertson, John Wilkerson
Postdocs Wanted
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Germanium Basics

• Internal Source Method from Fiorini
• 76Ge Endpoint 2039 keV
• Energy above many contaminants
• Except 208Tl, 60Co, 68Ge
• FWHM 3-4 keV around 2 MeV (0.2)
• Long experience with Ge bb decay
• Previous efforts found 2n at T1/2 1021 y
• Expect 0n at T1/2 4 x 1027 y
• Ready to go!
• Essentially no RD needed

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Majorana Overview

• 0nbb decay of 76Ge potentially measured at 2039
  keV
• Sensitive to effective Majorana n mass as low as
  0.02-0.07 eV
• Based on well known 76Ge detector technology
  plus
• Pulse-shape analysis
• Detector segmentation
• Ready to begin now
• Requires
• Deep underground location
• 500 kg enriched 85 76Ge
• 210 crystals, 12 segments each
• Advanced signal processing
• Special materials (low bkg)

Baseline Concept
See majorana.pnl.gov
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Collaboration ProgressOptimization and Prep for
Full Experiment
Multi Element Germanium Assay (MEGA) 162
natural Ge
MAJORANA 210 Ge detectors All enriched/segmented
Ten 21-crystal modules
g
Segmented Enriched Germanium Array
(SEGA) Segmented Ge
1 to 5 Crystals High energy n bkg Pulse analysis
test Materials screening
High density Materials qualification Cryo design
test Geometry test Powerful screening tool
Full Experiment
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Physics Goals
MEGA 162 natural Ge
MAJORANA 210 Ge detectors All enriched/segmented
Ten 21-crystal modules
SEGA Segmented Ge
Dark matter limit Precision 2nbb
Dark Matter limit Excited state bb T½ Other
Isotope 2nbb
Measure neutrino mass Majorana vs. Dirac
Character High dark matter sensitivity
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Majorana Baseline Concept
3-D model of baseline configuration

• Optimization underway of performance and risk
• Several low risk baseline designs possible
• Many segmentation schemes possible
• Alternative packaging, cooling, and shielding
  under consideration
• Nature of Ge crystals allows repackaging

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Sensitivity vs. Time

• Slow Baseline Gradual ramp to 100 kg/y - total
  500 kg 85 76Ge
• Fast Baseline (No ramp) 200 kg/y
• Present 0nbb 76Ge T1/2 limit rapidly surpassed
  (T1/2 gt 1.9 1025 y)

0nbb Half-Life
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One UG Basing Concept
Overall 14x14 Experiment Apparatus 5x5 DAQ/Contro
l 3x4 Cu Manufacturing Plating 3.5x8 Machining 6.
5x6 Plus Airlocks, changing, storage Minus Detecto
r Manufacturing
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We dont need 15m ceilings

• Several acceptable configurations
• Experiment and critical infrastructure in one
  breathing space
• Separate spaces for
• ApparatusDAQ/Control (12-15 foot ceiling useful)
• Electroplating lab (7.5 foot ceilings adequate)
• Detector manufacturing (7.5 foot ceilings
  adequate)

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Potential Majorana Layouts?
Apparatus plus Electroforming
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Majorana Needs

• Special Facilities
• Pure water electroforming
• Modest vibration control
• Modest LN supply or generator
• Calibration
• Past Lantern Mantles
• Future 26Al plus mixed std?
• Fab Processes
• Cu electroforming
• Clean machine shop
• Small fume hood
• Storage
• Detector fab
• Crystal fab (optional)
• Detector finishing

• Basic Requirements
• Depth Deep
• Space See Diagram
• Power tens of kW
• Temperature
• Apparatus modestly cool
• Electroplating comfortable
• Detector fab comfortable
• Background Tolerances
• Muons 6k mwe is great!
• Gammas 50 cm Pb
• N(fission, (a,n)) Modest Poly
• N(gt10MeV) Deep is good
• Radon Local scrubbing plus LN boiloff backflow

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Low-Background Electroformed Copper

• Purity refined via IGEX experience
• Strength equal to OFHC
• Can be easily formed into thin, low-mass parts
• Parts shown are for the MEGA array

Electroformed cups shown have wall thickness of
only 250 mm!
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Recent Crystal Packaging Test(MEGA)
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Conclusions

• Unprecedented confluence
• Krasnoyarsk availability/Neutrino mass interest/
  Underground development/Crystal capacity
• High Density
• reduced shielding and footprint
• Low Risk
• proven technology/ modular instrument /
  relocatable
• Experienced Collaboration
• long bb track record
• robust and growing
• Neutrino mass sensitivity
• potential for discovery