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The MAJORANA Project


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Title: The MAJORANA Project

The MAJORANA Project
  • Science of ??
  • MAJORANA Demonstrator
  • Detailed description
  • Some technical issues
  • Toward a 1-ton Experiment

What is ???
Fig. from Deep Science
Fig. from arXiv0708.1033
???and the neutrino
  • ??(0?) decay rate proportional to neutrino mass
  • Most sensitive technique (if Majorana particle)
  • Decay can only occur if Lepton number
    conservation is violated
  • Leptogenesis?
  • Decay can only occur if neutrinos are massive
    Majorana particles
  • Critical for understanding incorporation of mass
    into standard model
  • ???is only practical experimental technique to
    answer this question
  • Fundamental nuclear/particle physics process

bb Decay Rates
G are calculable phase space factors. G0n
Q5 M are nuclear physics matrix elements. Hard
to calculate. mn is where the interesting
physics lies.
Past Results
Elliott Vogel Annu. Rev. Part. Sci. 2002 52115
A Recent Claimhas become a litmus test for
future efforts
??? is the search for a very rare peak on a
continuum of background. 70 kg-years of
data 13 years The feature at 2039 keV is
arguably present.
NIM A522, 371 (2004)
Future Data Requirements
  • Why wasnt this claim sufficient to avoid
  • Low statistics of claimed signal - hard to repeat
  • Background model uncertainty
  • Unidentified lines
  • Insufficient auxiliary handles
  • Result needs confirmation or repudiation

KKDC Claim
50 meV Or 1027 yr
Atmospheric Scale
Solar Scale
An Ideal ExperimentMaximize Rate/Minimize
  • Large Mass ( 1 ton)
  • Large Q value, fast bb(0n)
  • Good source radiopurity
  • Demonstrated technology
  • Ease of operation
  • Natural isotope
  • Small volume, source detector
  • Good energy resolution
  • Slow bb(2n) rate
  • Identify daughter in real time
  • Event reconstruction
  • Nuclear theory

Background Considerations
At atmospheric scale, expect a signal rate on the
order of 1 count/tonne-year
  • ??(2?)
  • natural occurring radioactive materials
  • neutrons
  • long-lived cosmogenics

The usual suspects
  • ??(2?)
  • For the current generation of experiments,
    resolutions are sufficient to prevent tail from
    intruding on peak. Becomes a concern as we
    approach the ton scale
  • Resolution, however, is a very important issue
    for signal-to-noise
  • Natural Occurring Radioactive Materials
  • Solution mostly understood, but hard to implement
  • Great progress has been made understanding
    materials and the U/Th contamination,
  • Elaborate QA/QC requirements
  • Future purity levels greatly challenge assay
  • Some materials require levels of 1?Bq/kg or less
    for ton scale expts.
  • Sensitivity improvements required for ICPMS,
    direct counting, NAA

As we approach 1 cnt/ton-year,a complicated mix
  • Long-lived cosmogenics
  • material and experimental design dependent
  • Minimize exposure on surface of problematic
  • Development of underground fabrication
  • Neutrons (elastic/inelastic reactions,
    short-lived isotopes)
  • (?,n) up to 10 MeV can be shielded
  • High-energy-? generated n are a more complicated
  • Depth and/or well understood anti-coincidence
  • Rich spectrum and hence difficult at these low
    rates to discern actual process, e.g. (n,n?)
    reactions - which isotope/level
  • Simulation codes are imprecise wrt low-energy
    nuclear physics
  • Low energy nuclear physics is tedious to
    implement and verify

1-ton Ge - Projected Sensitivity vs. Background
Goal is to achieve ultra-low backgrounds of less
than 1 count per ton of material per year in the
ROI about the bb(0n) Q-value energy.
MAJORANA Collaboration Goals
  • Actively pursuing the development of RD aimed at
    a 1 tonne scale 76Ge 0???-decay experiment.
  • Technical goal Demonstrate background low enough
    to justify building a tonne scale Ge experiment.
  • Science goal build a prototype module to test
    the recent claim of an observation of 0???. This
    goal is a litmus test of any proposed technology.
  • Work cooperatively with GERDA Collaboration to
    prepare for a single international tonne-scale Ge
    experiment that combines the best technical
    features of MAJORANA and GERDA.
  • Pursue longer term RD to minimize costs and
    optimize the schedule for a 1-tonne experiment.

Support As a RD Project by DOE NP NSF PNA
76Ge offers an excellent combination of
capabilities sensitivities.
(Excellent energy resolution, intrinsically clean
detectors, commercial technologies, best 0???
sensitivity to date)
  • 60-kg of Ge detectors
  • 30-kg of 86 enriched 76Ge crystals required for
    science goal 60-kg for background sensitivity
  • Examine detector technology options focus on
    point-contact detectors for DEMONSTRATOR
  • Low-background Cryostats Shield
  • ultra-clean, electroformed Cu
  • naturally scalable
  • Compact low-background passive Cu and Pbshield
    with active muon veto
  • Agreement to locate at 4850 level at Sanford Lab
  • Background Goal in the 0????peak ROI(4 keV at
    2039 keV)
  • 1 count/ROI/t-y (after analysis cuts)

  • Expected Sensitivity to 0???(30 kg enriched
    material, running 3 years, or 0.09 t-y of 76Ge
  • T1/2 ? 1026 y (90 CL).Sensitivity to ltm?gt lt 140
    meV (90 CL) Rod05,err.

Cosmogenic 68Ge and 60Co
2.9 MeV
68Ge and 60Co are the dangerous internal
backgrounds For 60-kg enriched detector,
initially expect 60 68Ge decays/day. t1\2 288
d Minimize exposure on surface during enrichment
and fabrication PSD, segmentation, time
correlation cuts are effective at reducing these
Point Contact Detectors
Hole vdrift (mm/ns) w/ paths, isochrones
Barbeau et al., JCAP 09 (2007) 009 Luke et al.,
IEEE trans. Nucl. Sci. 36 , 926(1989).
Point Contact Detectors
Realization that a design based on commercial
BEGe detectors might be advantageous.
Front End Electronics
Pulse Reset
Resistive Feedback
COGENT front ends (U Chicago)
UW Hybrid Design
LBNL Design
String Designs
First Module
  • 18 natural-Ge Canberra BEGes on order
  • Ø 702.5 mm, h 302.5 mm
  • 579 g active mass
  • contact r lt 6.5 mm (5 mm nom.)
  • Front surface metalized for HV
  • 4 to 6 crystals per string
  • Front-ends mounted next to the crystal
  • Closed cold plate and beefier Cu in detector
    mounts for added strength

Shield Design
Side View
Top View
Sanford Lab Layout - Draft
Alternative Separation of 76Ge
  • Demonstrator needs roughly 50 kg of 76Ge
  • Russian centrifuge separation is the project
    baseline at 60/g
  • ECP of Zelenogorsk supplied all the isotope for
    IGEX and HM experiments
  • Evaluated possible alternative methods for
  • thermal diffusion enrichment (SBIR developed -
    ready for test run)
  • acoustic enrichment (immature)
  • plasma enrichment (promising)
  • UCLA spinoff, Nonlinear Ion Dynamics (NID),
    developing plasma separation isotope business -
    NIH funded development of machine for 18O
  • Majorana has contracted NID to produce a report
    and 76Ge material sample

Electroforming and Cu Purity - Material purity
  • Copper Cleanliness
  • Assay data indicates that CuSO4 in bath is source
    of Th in part
  • Producing our own CuSO4 from pure starting
    materials has been more successful in producing
    clean Cu then re-crystalizing the CuSO4.
  • Initial ICPMS study in 2005
  • 5-10 mBq/kg, limitation in materials, prep
  • Improved to 2-4 mBq/kg
  • Goal lt1 mBq/kg
  • Copper Production
  • Plating to several cm without machining
  • Presently plating 2-5 mil/day
  • Developing configurations, waveforms, recipes to
    improve buildup rate
  • Purity limitations vs. buildup rate will come
    from 228Th tracer studies.

Underground electroforming at WIPP - Cu purity
  • Electroform a part underground
  • Electroformed Cu is extremely pure, very little
    Th/U. By electroforming UG, the cosmogenic
    isotope Co-60 should be eliminated also
  • Demonstrate that one can safely form a part
    underground in a highly regulated environment
  • WIPP follows a strict safety protocol directed
    by DOE and MSHA
  • Low voltage system to plate Cu from 1.2 M acid
    solution onto SS mandrel

Test Part Copper Beaker fabricated 660 gm 160
mm high, 110 mm diameter Wall thickness 1
mm 10 days of UG electroforming in two
stretches Solution is 1.5 kg copper sulfate
dissolved in 16 L 1.2M sulfuric acid Part
removed from mandrel by successive dunks in
boiling water and liquid nitrogen
Low-background cryostat testing at WIPP - Large
  • Progress in the MEGA cryostat
  • Installed and operated Ge detectors underground
    at WIPP in low-background apparatus
  • Installed Ge detectors in clean room environment
  • Connected and tested associated electronics
  • Brought system to vacuum and cooled with LN
  • Collected 17-hour background run from three Ge

Test Cryostat for String Design - Large cryostats
  • Detector String
  • Cryostat holds 3 strings - Each string holds 3
  • Strings hang inside detector hanger
  • Goals
  • Study thermal properties of the Majorana crystal
    cooling design
  • Explore detector string design and mounting
  • Operate a string of cooled detectors under vacuum
  • Thermal Test
  • Stainless steel detector blanks (above) similar
    thermal mass and emissivity of Ge crystals
  • Thermocouples mounted on blanks and copper parts
    show temperature response when cooled (above)
  • Successful cooling of blanks by weak conduction

HI?S FEL Runs to Characterize SEGA -
Reference Design Backgrounds
  • Background modeling
  • Simulated major background sources for detector
    components in a 57-cystal array shield using
  • Calculated total backgrounds individually for
    each detector technology under consideration
  • Results
  • Cu purity of 0.3 mBq/kg is required sizeable
    contribution from 208Tl in the cryostat and
  • Higher rejection of segmented designs is roughly
    balanced by introduction of extra readout
  • P-PC appears to achieve the best backgrounds with
    minimal readout complexity.

Better Sensitivity New Backgrounds
Pb target in neutron beam arXiv0809.5074
  • Specific Pb gamma rays are problematic
  • 206Pb has a 2040-keV ? ray
  • 207Pb has a 3062-keV ? ray
  • 208Pb has a 3060-kev ? ray
  • Neutron interactions in Pb can excite these
  • The DEP of the 3062 keV ? ray is a single site
    energy deposit at ßß Q-value

ORCA Object-Oriented Real-time Control and
AcquisitionHowe et al. IEEE Transactions on
Nuclear Science, 51 (3), 878-83
  • Features
  • Run time configuration, on-the-fly configurable
    acquisition tasks, run control, data monitoring,
    data replay capabilities, ROOT support.
  • Real-time data stream can be broadcast to remote
  • Supports operator and expert user modes
  • Object-oriented throughout (Objective-C), very
    modular, very easy to add new objects
  • Uses XML for file headers and configuration
  • Hardware Support
  • VME, CAMAC, GPIB, cPCI, USB, IEEE 1394, Serial
  • Usage
  • SNO NCD, KATRIN pre-spect., CENPA accelerator,
    CENPA test stands, UW Radiology,
    MAJORANA(development), LANL, FZK test stands

Object Catalog
Drag n Drop to Place Objects
Configuration View
  • Bare enrGe array in liquid argon
  • Shield high-purity liquid Argon / H2O
  • Phase I (late 2009) 18 kg (HdM/IGEX diodes)
  • Phase II (mid 2009) add 20 kg new detectors -
    Total 40 kg
  • Modules of enrGe housed in high-purity
    electroformed copper cryostat
  • Shield electroformed copper / lead
  • Initial phase RD demonstrator module Total 60
    kg (30 kg enr.)
  • Joint Cooperative Agreement
  • Open exchange of knowledge technologies (e.g.
    MaGe, RD)
  • Intention is to merge for 1 ton exp. Select best
    techniques developed and tested in GERDA and

The MAJORANA Collaboration (Feb. 2009) Note Red
text indicates students
Black Hills State University, Spearfish, SD Kara
Keeter Duke University, Durham, North Carolina ,
and TUNL James Esterline, Mary Kidd, Werner
Tornow Institute for Theoretical and
Experimental Physics, Moscow, Russia Alexander
Barabash, Sergey Konovalov, Igor Vanushin,
Vladimir Yumatov Joint Institute for Nuclear
Research, Dubna, Russia Viktor Brudanin, Slava
Egorov, K. Gusey,Oleg Kochetov, M. Shirchenko,
V. Timkin, E. Yakushev Lawrence Berkeley
National Laboratory, Berkeley, California andthe
University of California - Berkeley Mark Amman,
Marc Bergevin, Yuen-Dat Chan, Jason Detwiler,
Brian Fujikawa, Kevin Lesko, James Loach, Paul
Luke, Alan Poon, Gersende Prior, Craig Tull, Kai
Vetter, Harold Yaver, Sergio Zimmerman Los
Alamos National Laboratory, Los Alamos, New
Mexico Steven Elliott, Victor M. Gehman, Vincente
Guiseppe, Andrew Hime, Kieth Rielage, Larry
Rodriguez, Jan Wouters North Carolina State
University, Raleigh, North Carolina and
TUNL Henning Back, Lance Leviner, Albert
Young Oak Ridge National Laboratory, Oak Ridge,
Tennessee Jim Beene, Fred Bertrand, Thomas V.
Cianciolo, Ren Cooper, David Radford, Krzysztof
Rykaczewski, Robert Varner, Chang-Hong Yu
Osaka University, Osaka, Japan Hiroyasu Ejiri,
Ryuta Hazama, Masaharu Nomachi, Shima Tatsuji
Pacific Northwest National Laboratory,
Richland, Washington Craig Aalseth, James Ely,
Tom Farmer, Jim Fast, Eric Hoppe, Brian
Hyronimus, Marty Keillor, Jeremy Kephart, Richard
T. Kouzes, Harry Miley, John Orrell, Jim Reeves,
Bob Thompson, Ray Warner Queen's University,
Kingston, Ontario Art McDonald University of
Alberta, Edmonton, Alberta Aksel
Hallin University of Chicago, Chicago,
Illinois Phil Barbeau, Juan Collar, Nicole
Fields, Charles Greenberg, University of North
Carolina, Chapel Hill, North Carolina and
TUNL Melissa Boswell, Padraic Finnerty, Reyco
Henning, Mark Howe, Michael Akashi-Ronquest,
Sean MacMullin, Jacquie Strain, John F.
Wilkerson University of South Carolina,
Columbia, South Carolina Frank Avignone, Richard
Creswick, Horatio A. Farach, Todd
Hossbach University of South Dakolta,
Vermillion, South Dakota Tina Keller, Dongming
Mei, Chao Zhang University of Tennessee,
Knoxville, Tennessee William Bugg, Yuri
Efremenko University of Washington, Seattle,
Washington John Amsbaugh, Tom Burritt, Peter J.
Doe, Jessica Dunmore, Robert Johnson, Michael
Marino, Mike Miller, Allan Myers, R. G. Hamish
Robertson, Alexis Schubert, Tim Van Wechel
Begin construction of 1-tonne
  • Primary focus is on first module, 18 BEGes
  • Much design work and prototyping in progress.
  • Final detector mount / cryostat design and
    readout down-select for first module in the
  • Sanford Lab preparations are proceeding rapidly,
    hope to begin installation late 2009
  • Next collaboration meeting June 2-4 at Sanford
    Lab in South Dakota


MAJORANA technical progress - past year
  • Materials Assay - Samples of low-activity
    plastics and cables have been obtained for
    radiometric counting and neutron activation
    analysis. Additional improvements have been
    gained in producing pure Cu through
    electroforming at PNNL and we have established an
    operating pilot program demonstrating
    electroforming underground at WIPP.
  • Ge Enrichment - Options available for germanium
    oxide reduction, Ge refinement, and efficient
    material recycling were considered. We have a
    plan to develop this capability located near
    detector fabrication facilities in Oak Ridge. 
  • Detectors - Additional p-type point contact (PPC)
    detectors have been ordered, using FY08 DUSEL RD
    funds as well as LDRD or institutional funds. 18
    of these detectors are intended for the first
    cryostat. Efforts to deploy a prototype
    low-background N-type segmented contact (NSC)
    detector using our enriched SEGA crystal are
    underway.  This will allow us to test low-mass
    deployment hardware and readout concepts while
    working in conjunction with a detector
  • Cryostat Modules - A realistic prototype
    deployment system has been constructed at LANL. 
    Modifications to this design are in place to
    permit prototyping of the current string design.
  • DAQ Electronics Decision to use GRETINA
    digitizers. Preparing to place order. The slow
    control systems were exercised in a prototype
    deployment system at LANL.
  • Facilities - Designs for an underground
    electroforming facility at the 800 level and a
    detector laboratory located on the 4850 level in
    the Homestake Mine are nearly complete in
    collaboration with the Sanford Laboratory design
    team. The schedule indicates the labs should be
    ready near the end of CY2009.
  • Simulations - Several papers describing
    background studies have been published.
  • Management - Task specific groups have been
    formed based on revised RD WBS.  Task leaders
    and their deputies have organized and held a
    number of workshops including Level 2 Task
    Leaders (Berkeley), Sanford/DUSEL planning (Lead,
    SD), Ge Enrichment (Oak Ridge), Cryostat Module
    (Seattle, Berkeley), Materials and Assay
    (Berkeley), and PPC Detectors (Oak Ridge). GERDA
    and MAJORANA collaborators have been attending
    the other collaborations meetings and updated
    the letter of intent to collaborate on a
    tonne-scale experiment.

Refinements to the MAJORANA Demonstrator
  • Concentrate on P-PC Detectors.
  • Advantages of cost and simplicity, with no loss
    of physics reach.
  • Will continue N-SC RD utilizing SEGA crystal.
  • Considering additional physics one can do with
    low-energy P-PC detectors.
  • exploits low-energy sensitivity (100 eV
    threshold) of P-PC detectors
  • In joint partnership with agencies and
    institutions, plan early implementation of
    natural Ge P-PC sub-module.
  • Future commitments of institutional funds
    dependent on agency support.

The need for enriched 76Ge
  • Background Risks
  • Achieving acceptable backgrounds in natGe
    detectors is a necessary, but not a sufficient
    condition to demonstrate our background goal
  • Past examples of significant background
    differences between natural and enriched
  • Require backgrounds a factor of 100 below
    previous Ge experiments
  • At such levels, previously unanticipated
    background sources can arise
  • Require 60 kg of total Ge to establish background
  • 50 needs to be enriched to assure comparable
    background levels 30 kg enrGe
  • Enrichment and purification can introduce
    impurities and physical differences that can
    impact subsequent chemistry
  • Require intrinsic enrGe detectors with isotopes
    of U and Th at the 10-15 g/g
  • Different isotopes of Ge have different
    cross-sections for cosmogenic activation
  • Cost Risks
  • Must develop and maintain separate production
    capabilities for reduction of GeO2 to Ge metal
    refinement to high purity Ge suitable for
    detector fabrication successful detector
  • For 1-tonne it may be necessary to perform some
    of these steps UG
  • Conclusion Must show in the Demonstrator phase
    that we can produce working enriched HPGe
    detectors with acceptable backgrounds.

Point contact Detectors
Detectors in hand
  • ORTEC PPC prototype gt500 g
  • Canberra BEGe for low-BG low-E studies
  • Inverted-coax PPC
  • Mini-PPCs for surface preparation studies

Front Ends Resistive Feedback
  • Trace proximity provides 1 pF capacitance
  • Silica or sapphire substrate provides thermal
  • Amorphous Ge resistor deposit in H environment
    gives proper R at low T
  • MX-120 FET
  • Possibility to add decoupling C inside feedback
    loop (substrate stands off HV)

Front Ends Pulsed Reset
COGENT front ends
UW Hybrid Design
  • Front-end and first stage hybrid design close
    the loop near the detector
  • Power dissipation and radioactivity levels may be
  • Currently prototyping