The MAJORANA D search for neutrinoless double beta decay · 2016-07-23 · – Prototype Module*:...

C. M. O’Shaughnessy Univ. of North Carolina & Triangle Universities Nuclear Laboratory

On behalf of the MAJORANA Collaboration

Office of Nuclear Physics

22 June 201522 – 26 June 2015

Madrid, Spain

The MAJORANA DEMONSTRATOR search for neutrinoless double beta decay

22 June 2015 The MAJORANA DEMONSTRATOR search for 0𝞶𝝱𝝱 2

Outline• 0νββ Sensitivity Considerations • MAJORANA DEMONSTRATOR Overview • Status of the DEMONSTRATOR

Neutrinoless ββ

• 2νββ — (A,Z)→(A,Z+2)+2e-+2ν̅eSM Allowed and observed in select even-even isotopes

• 0νββ — (A,Z)→(A,Z+2)+2e-

ΔL = 2

3The MAJORANA DEMONSTRATOR search for 0𝞶𝝱𝝱22 June 2015

Neutrinoless ββ

• Most sensitive experiments to date using 76Ge,130Te, and 136Xe have attained T1/2 > 1025 years

• Typical Source Mass — exposure times of 30 - 100 kg-years

2νββ0νββ


Expected 0νββ signals (cnts/tonne-year)

• Background Free 1/20νT"

#$

%

&'

−1∝ε ff ⋅ Iabundance ⋅Source Mass ⋅ Time

Half life (years)

~Signal (cnts/tonne-year)

1025 500

5x1026 10

5x1027 1

>1029 <0.05


• Background Limited

Expected 0νββ signals (cnts/tonne-year)

• Background Free 1/20νT"

#$

%

&'

−1∝ε ff ⋅ Iabundance ⋅Source Mass ⋅ Time

1/20νT"

#$

%

&'

−1∝ε ff ⋅ Iabundance ⋅

Source Mass ⋅ TimeBkg ⋅ ΔE

Half life (years)

~Signal (cnts/tonne-year)

1025 500

5x1026 10

5x1027 1

>1029 <0.05


• Background Limited

76Ge Sensitivity vs. Background


Exposure [ton-years]3−10 2−10 1−10 1 10 210 310

90%

Sen

sitiv

ity [y

ears

]1/

2G

e T

76

2410

2510

2610

2710

2810

2910

3010

Background free0.1 counts/ROI/t/y1.0 count/ROI/t/y10.0 counts/ROI/t/y

:ββIH minimum mQRPASMIBM-2EDF

Exposure [ton-years]3−10 2−10 1−10 1 10 210 310

DL

[yea

rs]

σ 3

1/2

Ge

T76

2410

2510

2610

2710

2810

2910

3010

Background free0.1 counts/ROI/t/y1.0 count/ROI/t/y10.0 counts/ROI/t/y

:ββIH minimum mQRPASMIBM-2EDF

76Ge Discovery vs. Background


0νββ Discovery Considerations

• Need large, highly efficient source mass • Desire extremely low (near-zero) backgrounds in the

0νββ peak region ➡Signal background 1:1 or better ➡Best possible resolution, ΔE, to minimize region of

interest • Want best possible energy resolution and/or

kinematical method to discriminate 0νββ from 2νββ

2νββ0νββ

Tonne scale experiments require backgrounds of

≤1 cts / ROI-t-y

Need independent observations from different isotopes


MAJORANA Collaboration

1027 May 2015 Wilkerson, MJD Annual Review

Black Hills State University, Spearfish, SD Kara Keeter

Duke University, Durham, North Carolina , and TUNL Matthew Busch

Institute for Theoretical and Experimental Physics, Moscow, Russia Alexander Barabash, Sergey Konovalov, Vladimir Yumatov

Joint Institute for Nuclear Research, Dubna, Russia Viktor Brudanin, M. Shirchenko, Sergey Vasilyev, E. Yakushev,

I. Zhitnikov

Lawrence Berkeley National Laboratory, Berkeley, California and the University of California - Berkeley

Nicolas Abgrall, Mark Amman, Paul Barton, Adam Bradley, Yuen-Dat Chan, Paul Luke, Susanne Mertens, Alan Poon,

Christopher Schmitt, Kai Vetter, Harold Yaver

Los Alamos National Laboratory, Los Alamos, New Mexico Pinghan Chu, Steven Elliott, Johnny Goett, Ralph Massarczyk, Keith

Rielage, Larry Rodriguez, Harry Salazar, Wenqin Xu

Oak Ridge National Laboratory Cristian Baldenegro-Barrera, Fred Bertrand, Kathy Carney,

Alfredo Galindo-Uribarri, Matthew P. Green, Monty Middlebrook, David Radford, Elisa Romero-Romero, Robert Varner, Brandon White,

Timothy Williams, Chang-Hong Yu

Osaka University, Osaka, Japan Hiroyasu Ejiri

Pacific Northwest National Laboratory, Richland, Washington Isaac Arnquist, Eric Hoppe, Richard T. Kouzes, Brian LaFerriere, John Orrell

South Dakota School of Mines and Technology, Rapid City, South Dakota Adam Caldwell, Cabot-Ann Christofferson, Stanley Howard,

Anne-Marie Suriano, Jared Thompson

Tennessee Tech University, Cookeville, Tennessee Mary Kidd

University of North Carolina, Chapel Hill, North Carolina and TUNL Tom Gilliss, Graham K. Giovanetti, Reyco Henning, Jacqueline MacMullin,

Samuel J. Meijer, Benjamin Shanks, Christopher O’Shaughnessy, Jamin Rager, James Trimble, Kris Vorren, John F. Wilkerson

University of South Carolina, Columbia, South Carolina Frank Avignone, Vince Guiseppe, David Tedeschi, Clint Wiseman

University of South Dakota, Vermillion, South Dakota Dana Byram, Ben Jasinski, Ryan Martin, Nathan Snyder

University of Tennessee, Knoxville, Tennessee Yuri Efremenko

University of Washington, Seattle, Washington Tom Burritt, Micah Buuck, Clara Cuesta, Jason Detwiler, Julieta Gruszko,

Ian Guinn, Greg Harper, Jonathan Leon, David Peterson, R. G. Hamish Robertson, Tim Van Wechel

• Located underground at 4850’ Sanford Underground Research Facility • Background Goal in the 0νββ peak region of interest (4 keV at 2039 keV)

3 counts/ROI/t/y (after analysis cuts) Assay U.L. currently ≤ 3.5 scales to 1 count/ROI/t/y for a tonne experiment

• 44 kg of Ge detectors – 29 kg of 87% enriched 76Ge crystals – 15 kg of natGe – Detector Technology: P-type, point-contact.

• 2 independent cryostats – ultra-clean, electroformed Cu – 20 kg of detectors per cryostat – naturally scalable

• Compact Shield – low-background passive Cu and Pb

shield with active muon veto

The MAJORANA DEMONSTRATORFunded by DOE Office of Nuclear Physics and NSF Particle Astrophysics, with additional contributions from international collaborators.

Goals: - Demonstrate backgrounds low enough to justify building a tonne scale experiment. - Establish feasibility to construct & field modular arrays of Ge detectors. - Searches for additional physics beyond the standard model.

1122 June 2015 The MAJORANA DEMONSTRATOR search for 0𝞶𝝱𝝱

MJD Implementation• Three Steps

– Prototype Module* : 7.0 kg (10) natGe 3 strings

– Module 1 : 16.8 kg (20) enrGe, 7 strings 5.7 kg (9) natGe

– Module 2 : (12.2 kg (14) enrGe, 7 strings 9.4 kg (15) natGe)


Commissioning start (Estimated)

Nov. 2013

Sept. 2014

(Sept. 2015)

In Shield (Estimated)

June 2014

May 2015

(End 2015)

✴ Same design as Cryos 1 & 2, but fabricated using OFHC Cu (non-electroformed) components.


MJD underground facilities• MJD UG site is Sanford Underground Research Laboratory

– Main MJD lab at 4850L Davis Campus, beneficial occupancy in May 2012. – Operating Temporary Cleanroom Facility (TCR) at 4850L Ross Campus since

Spring 2011.

13

-1586 -1000 0 1000 2000 3000 4000 5000 6000

-6

97

9-6

00

0-5

00

0-4

00

0-3

00

0-2

00

0

65206000500040003000200010000-1000

-1

87

3-3

00

0-4

00

0-5

00

0-6

00

0-6

97

9

U D

Yates

#3 Winze#6 Winze

Ross

Ramp to 4700L/5000L

Davis Campus

Ross Campus

MJD Main Lab

MJD Electroforming Lab

MJD Electroformed Cu

Electroforming Baths in TCR


• MJD operated 10 baths at the Temporary Clean Room (TCR) facility at the 4850’ level and 6 baths at a shallow UG site at PNNL. All copper was machined at the MJD Davis campus.

• The electroforming of copper for the DEMONSTRATOR successfully completed in April 2015. - 2474 kg of electroformed copper on the mandrels - 2104 kg after initial machining, - 1196 kg that will be installed in the DEMONSTRATOR.

• We continue to operate 5 baths in the TCR as backup stock for MJD and for other experiments. • Based on a very recent positive evaluation of the ground support at the TCR we are evaluating

continuing electroforming at the TCR or moving to the MJD Davis campus (EF Lab).

Inspection of EF copper on mandrels EF copper after machining

• Th decay chain (ave) ≤ 0.1 µBq/kg • U decay chain (ave) ≤ 0.1 µBq/kg


MJD Detector Unit

Also: • Electroformed Cryostats • Parylene coating / seals • Vespel, PEEK supports • Shields: Low-BG commercial Cu and Pb

We are working with a novel palette of ultra-pure materials, while also minimizing the total amounts

Clean Au+Ti traces on fused silica, amorphous Ge resistor, FET mounted with silver epoxy, EFCu + low-BG Sn contact pin

PFA + fine Cucoaxial cable

Electroformed

HPGe

Copper

PTFE

MJD Strings

• Up to 5 detectors are mounted in ‘strings’ • Strings are constructed and up to 7 loaded to

the module in a nitrogen purged glovebox16The MAJORANA DEMONSTRATOR search for 0𝞶𝝱𝝱22 June 2015

String with 3 EnrGe PPCs and 1 NatGe

BEGe

Modules


A Module is: • Cryostat • Thermosyphon, • Vacuum • Shield Section • All resting on a

movable bearing table

• Hov-air in routine use moving fully loaded modules

• Calibration system demonstrated

The MAJORANA DEMONSTRATOR search for 0𝞶𝝱𝝱22 June 2015

Compact Shield

18

Note keyed structure of shield

Veto + borated poly + poly

•Pb shield constructed •Outer Cu shield layer installed •Rn exclusion box installed •Poly layers being installed •Most veto panels operational (24 of 32)

0.23%

0.29%

0.63%

0.38%

0.60%

0.07%

0.39%

0.07%

0.09%

0.10%

0.05%

0.21%

0.17%

0.13%

0.03%

<0.01%

0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% 0.8% 0.9% 1%

Electroformed%Cu%

OFHC%Cu%Shielding%

Pb%shielding%

Cables%/%Connectors%

Front%Ends%

Ge%(U/Th)%

PlasLcs%+%other%

GeN68,%CoN60%(enrGe)%

CoN60%(Cu)%

External%γ,%(α,n)%

Rn,%surface%α%

Ge,%Cu,%Pb%(n,%n'γ)%

Ge(n,n)%

Ge(n,γ)%

direct%μ%+%other%

ν%backgrounds%

Background+Rate+(c/ROI3t3y)+

Electroformed%Cu%

GeN68,%CoN60%(enrGe)%

External%γ,%(α,n)%

Ge,%Cu,%Pb%(n,%n'γ)%

ν%backgrounds%

Natural%RadioacLvity%Cosmogenic%AcLvaLon%External,%Environmental%μNinduced%neutrinos%

Total:%3.5%c/ROINtNy%

DEMONSTRATOR Background Budget


Based on achieved assays of materials When UL, use UL as the contribution

MJD Goal: ≤ 3.0 cts / 4 keV / t-y

MJD Enriched Detectors• ORTEC/AMETEK : 30 PPC detectors (25.2 kg) UG at SURF. (64% yield) • Fabrication from Reprocessed Material (9.1 kg)

– Produced two 4.5 kg boules – Two additional detectors (2 kg) January 2015 – 2nd boule turned out to be n-type and

was regrown – Expect three more detectors in June

• Projected enriched detectors: - 35 enriched PPC detectors (29.2 kg)

Enriched ORTEC PPC UG (60Co CalibraRon)

Acceptance TesRng of enriched detectors UG


Comparison of measurements done at ORTEC and SURF within the vendor cryostat. All are better than specification.

P425

37A

P425

38A

P425

38B

P425

73A

P425

73B

P425

74A

P425

74B

P425

74C

P425

75A

P425

75B

P235

17A

P426

61A

P426

61B

P426

61C

P426

62A

P426

62B

P426

62C

P426

64A

P426

65A

P426

65B

P426

65C

P426

98A

P426

98B

P427

12B

P426

64B

P427

12A

P427

48A

P427

48B

P427

49A

P427

49B

FWH

M @

1.3

MeV

(keV

)

1.4

1.6

1.8

2

2.2

2.4

2.6ORTECSURF (vendor cryostat)ORTEC spec

MJD

F-20

14-1

0-14

-004

-R1


Prototype Module• Used for engineering and physics studies:

cleanliness, construction procedures, DAQ, vacuum, cryogenics, etc. • Installed and operated three strings of natGe detectors. • Took data in-shield from July 2014 to June 2015, removed for Module 2 construction • Dominant backgrounds as expected from prototyping materials:

solder, stainless steel screws, commercial copper, etc.

22

Prototype Cryostat inserted into the glove boxPrototype Cryostat with three installed strings


Module 1• Moved into shield end of May 2015. • Operating 23 of 29 detectors, 14 kg enriched, 3.7 kg natural. • Initial in-shield data taking summer 2015 followed by removal for shielding installation.

23

Energy[keV]0 500 1000 1500 2000 2500 3000

coun

ts/k

eV

1

10

210

310

410Energy Spectrum from an enriched PPC

Module 1 with 7 strings installed

228Th Calibration

Other Physics with MAJORANA


* Coherent neutrino nuclear scattering Barbeau et al., JCAP 09 (2007) 009; Luke et al., IEEE Trans. Nucl. Sci. 36, 926(1989).

• Low-E thresholds of PPC design allows for potential to cut cosmogenic backgrounds

–68Ge—68Ga time correlation cut • Also opens new possibilities for

experiments*: –WIMP Dark Matter Searches –Bosonic dark matter –Solar Axions –Low momentum transfer neutrino-electron

scattering –Fractionally charged Particles in cosmic-

rays –Pauli Exclusion Principle Violation –Lorentz Violation –Electron decay –…

• Enrichment reduces low-E backgrounds

22 June 2015 MAJORANA Collaboration Meetings

AcknowledgementsThis material is based upon work supported by the U.S.

Department of Energy, Office of Science, Office of Nuclear Physics. We acknowledge support from the Particle

Astrophysics Program of the National Science Foundation. This research uses these US DOE Office of Science User Facilities: the National Energy Research Scientific Computing Center and the Oak Ridge Leadership Computing Facility. We acknowledge support from the Russian Foundation for Basic Research. We thank our hosts and colleagues at the Sanford Underground

Research Facility for their support. The speaker also acknowledges support from the Center for Global Initiatives at

UNC-CH for attending this workshop.

25

Office of Nuclear Physics


MAJORANA DEMONSTRATOR Summary

26

- Copper electroforming for MJD is completed. - Detector production completed, including extra production from

reprocessed materials. - From assays, background budget projects to:

< 3.5 counts/4 keV/t-y, close to the original MJD goal of 3. - Prototype Module successfully completed its mission in June 2015. - Module 1: First low background module containing enriched detectors,

deployed in-shield late May 2015. - Commissioning and engineering runs for Module 1 have started. - Staging for Module 2 assembly has begun.


Supporting Slides


0νββ Sensitivity

28

Normal

Inverted

Even a null result will constrain the possible mass spectrum possibilities!

A mββ limit of ~15 meV would disfavor Majorana neutrinos in an inverted hierarchy.

50 meVOr ~ 1027 yr

N-type Coaxial P-type Point Contact

pp+ n+p+

n+

n


Point Contact Detectors (PPC)

• Ultra-low background requires PSA rejection of multi-site gamma events • Initially considered coaxial n-type detectors with modest segmentation • Chose P-type Point-Contact (PPC) detectors

– No deep hole; small point-like central contact – mm thick n+ outer contact – Localized weighting potential gives excellent multi-site rejection – Low capacitance (~ 1 pF) gives superb resolution at low energies

Luke et al., IEEE trans. Nucl. Sci. 36 , 926(1989); P. S. Barbeau, J. I. Collar, and O. Tench, J. Cosm. Astro. Phys. 0709 (2007).

29

N-type Coaxial P-type Point Contact

pp+ n+p+

n+

n

0

100

200

300

Cha

rge

Sign

al

0

20

40

60

Cur

rent

Sig

nal

200 600 1000 1400Time (ns)

0

100

200

300

400

0

20

40

60

80

200 600 1000 1400Time (ns)

a) Single-site b) Multi-site


Point Contact Detectors (PPC)

• Ultra-low background requires PSA rejection of multi-site gamma events • Initially considered coaxial n-type detectors with modest segmentation • Chose P-type Point-Contact (PPC) detectors

– No deep hole; small point-like central contact – mm thick n+ outer contact – Localized weighting potential gives excellent multi-site rejection – Low capacitance (~ 1 pF) gives superb resolution at low energies

Luke et al., IEEE trans. Nucl. Sci. 36 , 926(1989); P. S. Barbeau, J. I. Collar, and O. Tench, J. Cosm. Astro. Phys. 0709 (2007).

29

MALBEK • (Majorana Low-background BEGe Experiment at

KURF) • MALBEK is a 450-g R&D mod.- BEGe detector,

mounted in a low-background cryostat. R&D for Majorana

• MALBEK is operating since 2010 at KURF (1450 m.w.e.), located in Ripplemead, VA. Goals: – Systematically characterize spectrum. – R&D low-energy triggering and DAQ (low-energy pulses

difficult to distinguish from noise). – R&D PSA in low-energy region – Background model verification – Dark Matter search

4/27/15 Henning - BLV 2015, Amherst, MA 17


Backgrounds from Ge Crystals

68Ge(EC, T½ = 270 d) → 68Ga(90% 1.9 MeV β+, T½ = 68 min):

– Signal Selection in Time Selection tag 68Ge decay via K-shell (~10 keV, 86.4%), L-shell (~1 keV, 11.5%) de-excitations – If one observes 68Ge decay in a detector veto for several half-lives

Data from MJD R&D detector - MALBEK Simulations for the DEMONSTRATOR

31


90% Confidence Limit

32

4/27/15 Henning - BLV 2015, Amherst, MA 32

90%*confidence*limit*

WIMP mass (GeV)6 8 10 12 14 16 18 20

)2 (c

mSI

σW

IMP-

nucl

eon

-4310

-4210

-4110

-4010

-3910CoGeNT 2013 CoGeNT 2014 MLLUX 85 d TEXONOsuperCDMS LT (preliminary)

MALBEK constant cut

(preliminary)MALBEK 99% cut


Solar Axions

33

energy (keV)0 2 4 6 8 10 12

)-1

keV

-1 s

-2flu

x (c

m

3310

3410

3510

J. Redondo,

J. Cosmol. Astropart. Phys. 2013 no. 12, (2013) 008 • Solar axions are converted to x-rays in the detector —Primakoff effect

• Rates vary as the bragg conditions from the solar position


MJD String Characterization

34

Azimuthal Scanning Table

• String Performance and Characterization • Study drift times using 133Ba — utilizing 356 keV and 81 keV coincidences • PSA efficiency as a function of position

Crystal Axis Measurements

• Using Pulse Shape Simulation as a template can extract crystal axis from automated 133Ba scan data

• Still must minimize dataset and angular uncertainty • Work on implementing in string test cryostat • Plan to characterize a subset of detectors


0 50 100 150 200 250200

250

300

350

400

450

500

550

600

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difference:angle

0 0.5 1 1.5 2 2.5 3 3.5 4500

550

600

650

700

750

800

850

900

0

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400

600

800

1000

1200

1400

driftTime:phiPosScan Data Simulated Drift Times

Angle (rad)Angle (deg)

Drif

t Tim

e

Drif

t Tim

e (+

offs

et)

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