The M AJORANA Project

The MAJORANA Project

• Science of • MAJORANA Demonstrator

• Detailed description• Some technical issues

• Toward a 1-ton Experiment

Steve Elliott

What is ?

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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


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 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


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


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


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


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


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)


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.]



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


Point Contact Detectors


Realization that a design based on commercial “BEGe” detectors might be advantageous.

Front End Electronics


COGENT front ends(U Chicago)

UW “Hybrid” Design

Pulse Reset Resistive Feedback

LBNLDesign

String Designs


First Module


• 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

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Shield Design


Top View

Side 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 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



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

http://pnnlsp1.pnl.gov/sites/GUARD/8C%20Cu%20Electroforming/DSCN0787.JPG

http://pnnlsp1.pnl.gov/sites/GUARD/Electroforming%20Cu%20%20SolidWorks/with%20copper%20nuggets/cross-section%205.jpg

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


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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%


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.


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


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



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


• 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


• EXTRAS


• 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


–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


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.


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


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•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


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

The M AJORANA Project

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