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The M AJORANA Project. Science of M AJORANA Demonstrator Detailed description Some technical issues Toward a 1-ton Experiment. What is ?. Fig. from Deep Science. Fig. from arXiv:0708.1033. and the neutrino. (0 ) decay rate proportional to neutrino mass - PowerPoint PPT Presentation
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The MAJORANA Project
• Science of • MAJORANA Demonstrator
• Detailed description• Some technical issues
• Toward a 1-ton Experiment
Steve Elliott
What is ?
Fig
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Fig. from arXiv:0708.1033
April 7, 2009 2
Steve Elliott
(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 modelis only practical experimental technique to answer this
question• Fundamental nuclear/particle physics process
and the neutrino
April 7, 2009 3
Decay Rates
Γ2ν =G2νM2ν2
Γ0ν =G0νM0ν2mν
2
G are calculable phase space factors.G0 ~ Q5
|M| are nuclear physics matrix elements.Hard to calculate.
m is where the interesting physics lies.
Steve ElliottApril 7, 2009 4
Past Results
Elliott & VogelAnnu. Rev. Part. Sci. 2002 52:115
48Ca >5.8x1022 y <(3.5-22) eV
76Ge >1.9x1025 y <0.35 eV
76Ge >1.6x1025 y <(0.33-1.35) eV
76Ge =1.2x1025 y =0.44 eV
82Se >2.1x1023 y <(1.2-3.2) eV
100Mo >5.8x1023 y <(0.6-2.7) eV
116Cd >1.7x1023 y <1.7 eV
128Te >7.7x1024 y <(1.1-1.5) eV
130Te >3.0x1024 y <(0.41-0.98) eV
136Xe >4.5x1023 y <(1.8-5.2) eV
150Nd >1.2x1021 y <3.0 eV
CURE
Steve ElliottApril 7, 2009 5
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 data13 years
The “feature” at 2039 keV is arguably present. NIM
A52
2, 3
71 (
200
4)
Steve ElliottApril 7, 2009 6
Steve Elliott
Future Data Requirements
Why wasn’t this claim sufficient to avoid controversy?
• Low statistics of claimed signal - hard to repeat measurement• Background model uncertainty• Unidentified lines• Insufficient auxiliary handles
Result needs confirmation or repudiation
April 7, 2009 7
50 meVOr ~ 1027 yr
Normal
Inverted
Solar Scale
Atmospheric Scale
KKDC Claim
Steve ElliottApril 7, 2009 8
An Ideal ExperimentMaximize Rate/Minimize Background
Large Mass (~ 1 ton)Large Q value, fast (0)
Good source radiopurityDemonstrated technology
Ease of operationNatural isotope
Small volume, source = detectorGood energy resolution
Slow (2) rateIdentify daughter in real time
Event reconstructionNuclear theory
mββ ∝bΔEMtlive
⎛
⎝ ⎜ ⎜
⎞
⎠ ⎟ ⎟
14
Steve ElliottApril 7, 2009 9
Background Considerations
(2)
• natural occurring radioactive materials
• neutrons
• long-lived cosmogenics
At atmospheric scale, expect a signal rate on the order of 1 count/tonne-year
Steve ElliottApril 7, 2009 10
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, purification
• Elaborate QA/QC requirements
– Future purity levels greatly challenge assay capabilities• Some materials require levels of 1Bq/kg or less for ton scale expts.• Sensitivity improvements required for ICPMS, direct counting, NAA
Steve ElliottApril 7, 2009 11
As we approach 1 cnt/ton-year,a complicated mix emerges.
• Long-lived cosmogenics– material and experimental design dependent– Minimize exposure on surface of problematic materials– 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 problem
• Depth and/or well understood anti-coincidence techniques• 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
Steve ElliottApril 7, 2009 12
1-ton Ge - Projected Sensitivity vs. Background
13
Goal is to achieve ultra-low backgrounds of less than 1 count per ton of material per year in the ROI about the (0) Q-value energy.
April 7, 2009 Steve Elliott
MAJORANA
Actively pursuing the development of R&D 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 R&D to minimize costs and optimize the schedule for a 1-tonne experiment.
MAJORANA Collaboration Goals
Support: As a R&D Project by DOE NP & NSF PNA
April 7, 2009 15Steve Elliott
• 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 Pb
shield with active muon veto
• Agreement to locate at 4850’ level at Sanford Lab• Background Goal in the 0peak ROI(4 keV at 2039 keV) ~ 1 count/ROI/t-y (after analysis cuts)
The MAJORANA DEMONSTRATOR Module76Ge offers an excellent combination of capabilities & sensitivities.
(Excellent energy resolution, intrinsically clean detectors, commercial technologies, best 0 sensitivity to date)
April 7, 2009 16Steve Elliott
MAJORANA DEMONSTRATOR Overview
April 7, 2009 Steve Elliott 17
MAJORANA DEMONSTRATOR Module Sensitivity
• Expected Sensitivity to 0(30 kg enriched material, running 3 years, or 0.09 t-y of 76Ge exposure)
T1/2 1026 y (90% CL).Sensitivity to <m> < 140 meV (90% CL) [Rod05,err.]
April 7, 2009 18Steve Elliott
April 7, 2009 Steve Elliott 19
Cosmogenic 68Ge and 60Co
68Ge and 60Co are the dangerous internal backgroundsFor 60-kg enriched detector, initially
expect ~60 68Ge decays/day. 1\2 = 288 dMinimize exposure on surface during enrichment and fabrication
PSD, segmentation, time correlation cuts are effective at reducing these
68Ge68Ga
2.9 MeV68Zn
288d
Hole vdrift (mm/ns) w/ paths, isochrones
~x10
Barbeau et al., JCAP 09 (2007) 009; Luke et al., IEEE trans. Nucl. Sci. 36 , 926(1989).
Point Contact Detectors
April 7, 2009 20Steve Elliott
Point Contact Detectors
April 7, 2009 Steve Elliott 21
Realization that a design based on commercial “BEGe” detectors might be advantageous.
Front End Electronics
April 7, 2009 Steve Elliott 22
COGENT front ends(U Chicago)
UW “Hybrid” Design
Pulse Reset Resistive Feedback
LBNLDesign
String Designs
April 7, 2009 Steve Elliott 23
First Module
April 7, 2009 Steve Elliott 24
• 18 natural-Ge Canberra BEGe’s on order
– ∅ = 70±2.5 mm, h = 30±2.5 mm
– 579 g active mass
– contact r < 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
24
Shield Design
April 7, 2009 Steve Elliott 25
Top View
Side View
Sanford Lab Layout - Draft
April 7, 2009 Steve Elliott 26
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 separation:
– 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 production
• Majorana has contracted NID to produce a report and 76Ge material sample
Acoustic Enrichment Demonstration
NID Plasma Separator
ECP Centrifuges
April 7, 2009 27Steve Elliott
April 7, 2009 Steve Elliott 28
Electroforming and Cu Purity - Material purity
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.
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 Bq/kg, limitation in materials, prep– Improved to 2-4 Bq/kg– Goal <1 Bq/kg
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
1. Demonstrate that one can safely form a part underground in
a highly regulated environment
2. WIPP follows a strict safety protocol directed by DOE and
MSHA
3. 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
April 7, 2009 29Steve Elliott
30
Low-background cryostat testing at WIPP - Large cryostats
Progress in the MEGA cryostat
Installed and operated Ge detectors underground at
WIPP in low-background apparatus
1. Installed Ge detectors in clean room environment
2. Connected and tested associated electronics
3. Brought system to vacuum and cooled with LN
4. Collected 17-hour background run from three Ge
detectors
April 7, 2009 Steve Elliott
Steve Elliott
Test Cryostat for String Design - Large cryostats
Detector String
• Cryostat holds 3 strings - Each string holds 3 detectors
• Strings hang inside detector hanger
Goals• Study thermal properties of the Majorana crystal
cooling design• Explore detector string design and mounting
options• Operate a string of cooled detectors under vacuum
Thermal Test
1. Stainless steel “detector blanks” (above) similar thermal mass and emissivity of Ge crystals
2. Thermocouples mounted on blanks and copper parts show temperature response when cooled (above)
3. Successful cooling of blanks by weak conduction
April 7, 2009 31
HIγS FEL Runs to Characterize SEGA - background/detectors
SEGA is the first seg. detector made from enriched 76Ge
The FEL can be used as a tunable energy -ray source to get -rays and DEPs at Q
What is the background discrimination power of PSA and segmentation for -ray and DEP events at Q?
• Demonstrated PSA in SEGA detector for the first time
• Used 6 x 2 (φx z) segmentation to examine survival
probabilities for several segmentation schemes for DEP
and -ray events
• Performance should improve after electronic and
cryogenic upgrades
2 MeV DEP Survival: 59.7 ± 7.8%
2 MeV -Ray Survival: 27.9 ± 1.1%
3 MeV -Ray Survival: 28.5 ± 0.4%
April 7, 2009 32Steve Elliott
Reference Design Backgrounds
• Background modeling– Simulated major background sources for detector components in a 57-cystal array + shield using MaGe– 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 shield.– Higher rejection of segmented designs is roughly balanced by introduction of extra readout components.– P-PC appears to achieve the best backgrounds with minimal readout complexity.
April 7, 2009 33Steve Elliott
Better Sensitivity – New Backgrounds
• Specific Pb gamma rays are problematic backgrounds– 206Pb has a 2040-keV γ ray– 207Pb has a 3062-keV γ ray– 208Pb has a 3060-kev γ ray
• Neutron interactions in Pb can excite these levels
• The DEP of the ~3062 keV γ ray is a single site energy deposit at ββ Q-value
April 7, 2009 Steve Elliott 34
Pb target in neutron beamarXiv:0809.5074
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 applications/machines
• 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 storage
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
Configuration View
Object Catalog
Drag ‘n Drop to Place Objects
April 7, 2009 35Steve Elliott
April 7, 2009 Steve Elliott 36
MAJORANA - GERDA
• ‘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
GERDA
Joint Cooperative Agreement:• Open exchange of knowledge & technologies (e.g. MaGe, R&D)
• Intention is to merge for 1 ton exp. Select best techniques developed and tested in GERDA and MAJORANA
• Modules of enrGe housed in high-purity electroformed copper cryostat
• Shield: electroformed copper / lead • Initial phase: R&D demonstrator
module: Total ~60 kg (30 kg enr.)
MAJORANA
Black Hills State University, Spearfish, SDKara Keeter
Duke University, Durham, North Carolina , and TUNLJames 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, RussiaViktor Brudanin, Slava Egorov, K. Gusey,
Oleg Kochetov, M. Shirchenko, V. Timkin, E. Yakushev
Lawrence Berkeley National Laboratory, Berkeley, California and
the University of California - BerkeleyMark 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 MexicoSteven 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, TennesseeJim Beene, Fred Bertrand, Thomas V. Cianciolo, Ren Cooper, David Radford, Krzysztof Rykaczewski, Robert Varner, Chang-
Hong Yu
Osaka University, Osaka, JapanHiroyasu Ejiri, Ryuta Hazama, Masaharu Nomachi, Shima Tatsuji
Pacific Northwest National Laboratory, Richland, WashingtonCraig 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, OntarioArt McDonald
University of Alberta, Edmonton, AlbertaAksel Hallin
University of Chicago, Chicago, IllinoisPhil Barbeau, Juan Collar, Nicole Fields, Charles Greenberg,
University of North Carolina, Chapel Hill, North Carolina and TUNLMelissa Boswell, Padraic Finnerty, Reyco Henning, Mark Howe,
Michael Akashi-Ronquest, Sean MacMullin, Jacquie Strain, John F. Wilkerson
University of South Carolina, Columbia, South CarolinaFrank Avignone, Richard Creswick, Horatio A. Farach, Todd Hossbach
University of South Dakolta, Vermillion, South DakotaTina Keller, Dongming Mei, Chao Zhang
University of Tennessee, Knoxville, TennesseeWilliam Bugg, Yuri Efremenko
University of Washington, Seattle, WashingtonJohn 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
The MAJORANA Collaboration (Feb. 2009)Note: Red text indicates students
20152015
Begin construction of 1-tonne
DEMONSTRATOR Schedule
April 7, 2009 38Steve Elliott
• Primary focus is on first module, 18 BEGe’s• Much design work and prototyping in
progress. • Final detector mount / cryostat design and
readout down-select for first module in the summer
• Sanford Lab preparations are proceeding rapidly, hope to begin installation late 2009
• Next collaboration meeting: June 2-4 at Sanford Lab in South Dakota
Summary
April 7, 2009 39Steve Elliott
• EXTRAS
April 7, 2009 40Steve Elliott
• 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 R&D 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 manufacturer.
• 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 R&D 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 collaboration’s meetings and updated the letter of intent to collaborate on a tonne-scale experiment.
MAJORANA technical progress - past year
April 7, 2009 41Steve Elliott
–Concentrate on P-PC Detectors.• Advantages of cost and simplicity, with no loss of
physics reach.• Will continue N-SC R&D 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.
Refinements to the MAJORANA Demonstrator
April 7, 2009 42Steve Elliott
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 detectors
• 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 goal– 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 fabrication
• 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.
April 7, 2009 43Steve Elliott
Detectors in hand:Point contact Detectors
• ORTEC PPC prototype: >500 g
• Canberra BEGe for low-BG low-E studies
• Inverted-coax PPC
• Mini-PPCs for surface preparation studies
April 7, 2009 44Steve Elliott
45
•Trace proximity provides ~1 pF capacitance
•Silica or sapphire substrate provides thermal control
•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: Resistive Feedback
April 7, 2009 45Steve Elliott
Front Ends – Pulsed Reset
• Front-end and first stage “hybrid” design: close the loop near the detector
• Power dissipation and radioactivity levels may be challenging
• Currently prototyping
COGENT front ends UW “Hybrid” Design
46April 7, 2009 46Steve Elliott