# Presentation: 611042

## Double-Beta Decay and the Neutrino

**Steve Elliott**

***Nuclear Physics***

## Outline

**Double-Beta Decay and its relationship to the neutrino**
**The experimental context**
**Where we’re at and where we need to go**
**Proposed future work**
**A focus on the Majorana Project**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Why Neutrinos?

**properties are critical input to many physics questions**** **
**Particle/Nuclear Physics**
**Cosmology**
**Astrophysics**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Neutrinos: What do we want to know?

**Mass**

**Absolute**
**Mass**
**Scale**

**Relative**
**Mass**
**Scale**

**Dirac or Majorana**

******e**

******1**

******2**

******3**

**Mixing**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Oscillations and  Hierarchy Possibilities

**mass**

**Normal**

**Inverted**

**m****smallest**

**1**

**2**

**3**

**1**

**2**

**3**

**Atmos**

**Solar**

******e**** is composed of a large fraction of ********1****.**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Example  Decay Scheme

**In many even-even nuclei, ******** decay is **
**energetically forbidden. This leaves ******** **
**as the allowed decay mode.**

**Endpoint**
**Energy**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## (2): Allowed weak decay

**e****-**

**e****-**

**Z+2**

**Z+1**

**Z**

******e**

******e**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## (0): requires massive Majorana 

**e****-**

**e****-**

**Z+2**

**Z+1**

**Z**

******e**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Energy Spectrum for the 2 e-

**Endpoint**
**Energy**

- Steve Elliott, P-25 Seminar

- October 11, 2005

##  Decay Rates

**G are calculable phase space factors.**
**	****G****0******** ~ Q****5**
**|M| are nuclear physics matrix elements.**
**	****Hard to calculate.**
**m******** is where the interesting physics lies.**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## What about mixing, m& (0)?

******±1, CP cons.**

**Compare to ******** decay result:**

**virtual ******
**exchange**

**real ******
**emission**

**No mixing:**

**Compare to cosmology:**

- Steve Elliott, P-25 Seminar

- October 11, 2005

**Notes:**
Mbb is a coherent sum because the neutrino is virtual.
Mv is an incoherent sum because the neutrinos are real.

## Double Beta Decay

**Elliott & Vogel**
**Annu. Rev. Part. Sci. 2002 52:115**

| 48Ca | >1.4x1022 y | <(7.2-44.7) 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 | >1.9x1023 y | <(1.3-3.2) eV |
| 100Mo | >3.5x1023 y | <(0.7-1.2) eV |
| 116Cd | >1.7x1023 y | <1.7 eV |
| 128Te | >7.7x1024 y | <(1.1-1.5) eV |
| 130Te | >5.5x1023 y | <(0.37-1.9) eV |
| 136Xe | >4.4x1023 y | <(1.8-5.2) eV |
| 150Nd | >1.2x1021 y | <3.0 eV |

- Steve Elliott, P-25 Seminar

- October 11, 2005

## A Recent Claim

**The “feature” at 2038 keV is arguably present. This will probably require experimental testing.**

**Background level depends on intensity fit to other peaks.**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## 50 meV

**Or ~ 10****27**** yr**

**Normal**

**Inverted**

**Solar Scale**

**Atmospheric Scale**

**KKDC Claim**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## The UCI 82Se Experiment

- Photo: S. Elliott

- Steve Elliott, P-25 Seminar

- October 11, 2005

## The Heidelberg-Moscow Experiment

**Foundations of Physics, 32, (2002)**

- 8”

- Steve Elliott, P-25 Seminar

- October 11, 2005

## A Great Number of Proposed Experiments

| CARVEL | Ca-48 | 100 kg 48CaWO4 crystal scintillators |
| --- | --- | --- |
| COBRA | Te-130 | 10 kg CdTe semiconductors |
| DCBA | Nd-150 | 20 kg Nd layers between tracking chambers |
| NEMO | Mo-100, Various | 10 kg of  isotopes (7 kg of Mo), expand to superNEMO |
| CAMEO | Cd-114 | 1 t CdWO4 crystals |
| CANDLES | Ca-48 | Several tons CaF2 crystals in liquid scint. |
| CUORE | Te-130 | 750 kg TeO2 bolometers |
| EXO | Xe-136 | 1 ton Xe TPC (gas or liquid) |
| GEM | Ge-76 | 1 ton Ge diodes in liquid nitrogen |
| GENIUS | Ge-76 | 1 ton Ge diodes in liquid nitrogen |
| GERDA | Ge-76 | ~30-40 kg Ge diodes in LN, expand to larger masses |
| GSO | Gd-160 | 2 t Gd2SiO5:Ce crystal scint. in liquid scint. |
| Majorana | Ge-76 | ~180 kg Ge diodes, expand to larger masses |
| MOON | Mo-100 | Mo sheets between plastic scint., or liq. scint. |
| Xe | Xe-136 | 1.56 t of Xe in liq. Scint. |
| XMASS | Xe-136 | 10 t of liquid Xe |

- Steve Elliott, P-25 Seminar

- October 11, 2005

## “Selected” Projects

| CUORE | TeO2 Crystal bolometers |
| --- | --- |
| EXO | Liquid Xe TPC, daughter tag |
| GERDA | Bare Ge detectors in LN |
| Majorana | Ge det. in traditional cryostat |
| MOON | Scint. sandwiching Mo foils  |
| SuperNEMO | Foils, tracking and scint. |

**EXO**

**Majorana**

**CUORE**

**MOON**

**GERDA**

**NEMO**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## An exciting time for !

**< m******** ****> in the range**
**near 50 meV is very interesting.**

**For the next experiments:**

**For at least **
**one neutrino:**

## APS Study and M-180

**The APS neutrino study on the future US Neutrino Program made a few things clear. ****(****http://www.aps.org/neutrino/)**
**Double-beta decay as one of the highest priorities.**
**It recommends a staged approach beginning with 100-200 kg scaling later to 1 ton.**
**Precision measurement at degenerate scale**
**Followed by discovery potential at atmospheric scale**
_**Majorana has responded by developing a proposal for a 180-kg detector.**__** **_

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Why a precision measurement?

**If <m********> is near the degenerate scale:**
**We will want to compare results from several isotopes to fully understand the underlying physics.**
**A 10-20% decay rate measurement will allow effective comparisons between isotopes, when the matrix element uncertainty nears ~50%.**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Observation of (0) implies massive Majorana neutrinos, but:

**Relative rates between isotopes might discern light neutrino exchange and heavy particle exchange as the ******** mechanism.**
**Relative rates between the ground and excited states might discern light neutrino exchange and right handed current mechanisms.**
**Effective comparisons require experimental uncertainties to be small wrt theoretical uncertainties.**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## An Ideal ExperimentMaximize Rate/Minimize Background

**Large Mass (~ 1 ton)**
**Good source radiopurity**
**Demonstrated technology **
**Natural isotope**
**Small volume, source = detector**
**Good energy resolution**
**Ease of operation**
**Large Q value, fast ********(0********)**
**Slow ********(2********) rate**
**Identify daughter**
** ****Event reconstruction**
**Nuclear theory**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Ge Basics

**Large Mass (~ 1 ton):****	****	****120-500 kg of ****enr****Ge**
**Good source radiopurity:****	****Intrinsic Ge, well understood**
**Demonstrated technology:**** ****	****“Ready to Go”**
**Natural isotope**
**Small volume, source = det:****	****Fiorini “internal source method**
**Good energy resolution:****	****	****3-4 keV at 2039 keV, 0.2%**
**Ease of operation****	****	****High duty cycle operation**
**Large Q value, fast ********(0********)****	****2039 keV, above most radioactivities**
**Slow ********(2********) rate****	****	****	****10****21**** yrs**
**Identify daughter**
**Event reconstruction****	****	****segmentation, modularity, PSD**
**Nuclear theory****	****	****	****Low A - Shell Model and QRPA**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Favorable nuclear matrix element <M0>=2.4 [Rod05].
Reasonably slow 2 rate( = 1.4  1021 y).
Demonstrated ability to enrich from 7.44% to 86%. 
Ge as source & detectors.
Elemental Ge maximizes the source-to-total mass ratio.
Intrinsic high-purity Ge diodes.

**Reasonably slow 2******** rate****(************ = 1.4 ******** 10****21**** y).**
**Demonstrated ability to enrich from 7.44% to 86%. **
**Ge as source & detectors.**
**Elemental Ge maximizes the source-to-total mass ratio.**
**Intrinsic high-purity Ge diodes.**

**Strengths of Majorana**

**Excellent energy resolution — 0.16% at 2.039 MeV, 4-keV ROI**
**Powerful background rejection**
**Segmentation, granularity, timing, pulse shape discrimination**
**Best limits on 0********- decay used Ge (IGEX & Heidelberg-Moscow) ****	************> 1.9 ******** 10****25**** y**
**Well-understood technologies**
**Commercial Ge diodes**
**Existing, well-characterized  large Ge arrays (Gammasphere)**

**76****Ge offers a good combination of capabilities and sensitivities.  Majorana is ready to proceed, with demonstrated technologies.**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Majorana is scalable, allowing expansion to 1000 kg. 
The 180 kg Experiment (M180)
Reference Design
171 segmented, n-type, 86% enriched 76Ge crystals.
3 independent, ultra-clean, electroformed Cu cryostat modules.
Surrounded by a low-background passive shield and active veto.
Located deep underground (6000 mwe).
Background Specification in the 0peak ROI
	1 count/t-y
Expected Sensitivity to 0(for 3 years, or 0.46 t-y  of 76Ge exposure)
	T1/2 >= 5.5 x 1026 y (90% CL)
	<m> < 100 meV (90% CL) ([Rod05] RQRPA matrix elements)
  or a 10% measurement assuming a 400 meV value.

**The 180 kg Experiment (M180)**
**Reference Design**
**171 segmented, n-type, 86% enriched ****76****Ge crystals.**
**3 independent, ultra-clean, electroformed Cu cryostat modules.**
**Surrounded by a low-background passive shield and active veto.**
**Located deep underground (6000 mwe).**
**Background Specification in the 0********peak ROI**
**	**1 count/t-y
**Expected Sensitivity to 0********(for 3 years, or 0.46 t-y  of ****76****Ge exposure)**
- 	T1/2 >= 5.5 x 1026 y (90% CL)
- 	<m> < 100 meV (90% CL) ([Rod05] RQRPA matrix elements)
-   or a 10% measurement assuming a 400 meV value.

**The Majorana 180 kg Experiment Overview**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## 57 crystal module 
Conventional vacuum cryostat made with electroformed Cu.
Three-crystal stack are individually removable.

**57 crystal module **
**Conventional vacuum cryostat made with electroformed Cu.**
**Three-crystal stack are individually removable.**

**The Majorana Modular Approach**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Allows modular deployment, early operation
contains up to eight 57-crystal modules (M180 populates 3 of the 8 modules)
four independent, sliding units
40 cm bulk Pb, 10 cm ultra-low background shield
active 4 veto detector

**contains up to eight 57-crystal modules**** (M180 populates 3 of the 8 modules)**
**four independent, sliding units**
**40 cm bulk Pb, 10 cm ultra-low background shield**
**active 4******** veto detector**

**The Majorana Shield - Conceptual Design**

- Top view

- Steve Elliott, P-25 Seminar

- October 11, 2005

## The Majorana Reference Plan

**The Majorana Reference Plan**

- Enrichment**: ****Ge ~200 kg of intrinsic Ge metal, enriched to 86% in ****76****Ge, from the ECP in Russia**
- Transport**: ****surface ship this Ge to a detector manufacturing company in North America to produce Ge crystals, suitable for detector fabrication**
- Crystals**: ****produce approximately 180 1.1-kg, n-type, segmented Ge detectors with each segmentation geometry consisting of 2 segments **
- Module Assembly**: ****install detectors into Cu cryostats that have been electroformed underground**
- Module Installation**: ****install modules into an ultra-pure graded shield**
- Shielding**: ****incorporate an active, neutron and cosmic ray anti-coincidence detector (a veto system) into the Pb shield, deep underground**
- Front End Signals**: ****electronically read out the Ge detector signals with one high-bandwidth electronic channel per crystal and one low-bandwidth electronic channel per segment**
- Acquisition**: ****use commercial electronics technology for the data acquisition electronics**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Reducing Backgrounds - Two Basic Strategies

**Reducing Backgrounds - Two Basic Strategies**

**Directly reduce intrinsic, extrinsic, & cosmogenic activities**
**Select and use ultra-pure materials**
**Minimize all non “source” materials**
**Clean passive shield**
**Go deep — reduced ********’s & related induced activities**
**Utilize background rejection techniques**
**Energy resolution**
**0******** is a single site phenomenon**
**Many backgrounds have multiple site interactions**
**Granularity [multiple detectors]**
**Single Site Time Correlated****	****events (SSTC)**

-  Pulse shape discrimination (PSD)
-  Segmentation

- Demonstrating backgrounds requires:
-  Sensitive assay capabilities
-  Reliable and verified simulations

-  Active veto detector

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Cuts vs. Background Estimates

**Cuts vs. Background Estimates**

- 2039 keV peak plus cuts discriminates 0-decay from backgrounds

- Only known activities that occur at 2039 keV are very weak branches,with corresponding strong peaks that will appear elsewhere in the spectrum

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Estimated backgrounds in the 0-decay ROI

**Estimated backgrounds in the 0********-decay ROI**

**"Gross" indicates level of activity before any analysis cuts are applied. **
**"Net" indicates level of activity after cuts have been applied. **

- Steve Elliott, P-25 Seminar

- October 11, 2005

**Notes:**
The key is to attain 1 count/t-y, a nearly background free measurement.
To reach this goal requires utilizing all available reduction techniques.

## Maybe we’ll go to SNOLab

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Backgrounds for Majorana vs. Depth

**Backgrounds for Majorana vs. Depth**

- At Sudbury depth, 6000 mwe, calculate that about 15-20% of the expected background in ROI will be from  induced activities in Ge and the nearby cryostat materials (dominated by fast neutrons).

- Mei and Hime2005

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Readiness - Backgrounds 

**Readiness - Backgrounds **

- Simulations
**MaGe — GEANT4 based development package**
** ****being developed in cooperation with GERDA**
**Verified against a variety of Majorana low-background counting systems as well as others, e.g. MSU Segmented Ge, GERDA.**
**Fluka for ********-induced calculations, tested against UG lab data.**
- Assay
**Radiometric ****(Current sensitivity ~8 ********Bq/kg (2 pg/g) for ****232****Th)**
**Counting facilities at PNNL, Oroville (LBNL), WIPP, Soudan, Sudbury.**
**Mass Spect. ****(Current sensitivity 2-4 ********Bq/kg (0.5-1 pg/g) for ****232****Th)**
**Using Inductively Coupled Plasma Mass Spectrometry, have made recent progress on using ****229****Th tracer.**
**ICPMS has the requisite sensitivity (fg/g).**
**Present limitations on reagents being addressed by sub-boiling distillation.**
**ICPMS expected to reach needed 1 ********Bq/kg**** ****sensitivity****.**

-  **Key specifications**
- Cu at 1 Bq/kg (current  8 Bq/kg)
- cleanliness on a large scale (100 kg)

- Steve Elliott, P-25 Seminar

- October 11, 2005

**Notes:**
Need to say something here

## Readiness - Ultra-Pure Cu

**Readiness - Ultra-Pure Cu**

**Constructed electroformed Cu cryostat**
**30 cm dia x 30 cm high**
**Vacuum tested**
**Th chain purity in Cu is key**
**Ra and Th must be eliminated**
**Remove Ra, Th by ion exchange during electroforming**
**Starting stock <9 ********Bq/kg ****232****Th**
**Using ****229****Th tracer, demonstrated a factor of > 8000 Th rejection via electroforming**

- We expect to achieve the 1 Bq/kg 232Th specification

- Steve Elliott, P-25 Seminar

- October 11, 2005

## WIPP

**DOE Facility**
**Impressive****infrastructure**
**Modest depth****(1600 mwe)**
**Science as****add-on to****primary mission**
**Low background****counting lab****being built****MEGA-SEGA**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## WIPP Construction

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Assembling MEGA at WIPP

**Assembling MEGA at WIPP**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Readiness - Crystal Segmentation

**Readiness - Crystal Segmentation**

**Segmentation**
**Multiple conductive contacts**
**Additional electronics and small parts**
**Rejection greater for more segments**
**Background discrimination**
**Multi-site energy deposition**
**Simple two-segment rejection**
**Sophisticated multi-segment signal processing can provide 2 mm reconstruction of events**
**  **
**Demonstrated**
**(Note: reference plan has 2 segments)**
**MSU experiment (4x8 segments)**
**LANL Clover detector (2 segments)**
**LLNL+LBNL detector (8x5 segments)**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Segmentation test & simulation comparison

**Segmentation test & simulation comparison**

**Experiment with MSU/NSCL** **Segmented Ge Array**
**N-type,  8 cm  long,  7 cm  diameter**
**4x8 segmentation scheme: ****4 angular 90 degrees each, 8 longitudinal, 1 cm each**
**60****Co source**
**Segmentation successfully rejects backgrounds.**
**In good agreement with the simulations**

- Experiment

- GEANT

- Crystal

- 1x8

- 4x8

- Counts / keV / 106 decays

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Readiness - Pulse Shape Discrimination (PSD)

**Readiness - Pulse Shape Discrimination (PSD)**

**Excellent rejection for internal ****68****Ge and ****60****Co (x4)**
**Moderate rejection of external 2615 keV (x0.8)**
**Shown to work well with segmentation**
**Demonstrated capability**
**central contact**
**outer contacts**

- Central contact (radial) PSD

- PSD uses off-the-shelf waveform digitizers

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Demonstration of Segmentation & PSD

**Demonstration of Segmentation & PSD**

**We have data that demonstrates the hypothesis that the PSD and segmentation cuts are independent.**

**Clover detector**

- Th source

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Array Granularity detector-to-detector rejection

**Array Granularity *****detector-to-detector rejection***

**Simultaneous signals in two detectors cannot be 0******
**Requires tightly packed Ge**
**Successful against:**
**208****Tl and ****214****Bi**
**Supports/small parts (~5x)**
**Cryostat/shield (~2x)**
**Some neutrons**
**Muons (~10x)**
**Simulation and validation with Clover**

- ~ 40 cm

- Granularity is basically free and a powerful background suppressor.

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Readiness - Time Correlations

**Readiness - Time Correlations**

**68****Ge is worst initial raw background**
**68****Ge -> 10.367 keV x-ray, 95% eff**
**68****Ga -> 2.9 MeV beta**
**Cut for 3-5 half-lives after signals in the 11 keV X-ray window reduces ****68****Ga ******** spectrum substantially**
**Independent of other cuts**

- No cut

**3 ****, ****5**** t****1/2 ****cut**

- QEC = 2921.1

- SSTC is powerful against our largest raw background, 68Ge.

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Readiness - Ge Timeline & Backgrounds

**Readiness - Ge Timeline & Backgrounds**

**Conservative estimate of 100 days taken**
**Doubling this or spallation rate (1 atom/kg/day @ surface) adds 3% to total rate**

| Process Step | Minimum
Estimated
Time | Effective Time
(with shield) |
| --- | --- | --- |
| Enrichment: (ECP Zelenogorsk) | ~90 days | ~1 day |
| Shipping: Zelenogorsk to Oak Ridge | 32 days | 3.2 days |
| Production of metal and initial
refinement:  | 11 days | 11 days |
| Manufacturer’s zone refinement | 14 days | 14 days |
| Crystal growth:  | 4 days | 4 days |
| Mechanical preparation  | 3 days | 3 days |
| Detector Fabrication | 7 days | 7 days |
| Total | 161 days | 44.2 days |

- Shipping Concept: 2m cube

- Storage Concept: 4m cube

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Schedule

**Schedule**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Majorana Sensitivity: Realistic runtime 

**Majorana Sensitivity: Realistic runtime **

- Steve Elliott, P-25 Seminar

- October 11, 2005

## To deduce m from , one needs Matrix Elements

**If ******** is observed, the qualitative physics conclusions are profound regardless of |M|.**
**There are many calculations of |M|. Which should be used to deduce m********?**
**How do we interpret the uncertainty associated with the nuclear physics?**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Progress in Understanding the Matrix Element Uncertainty

**Previous spread is mostly due to the various implementations of QRPA.**
**Rodin et al. show that QRPA results tighten up (typically to ~20% uncertainty in half life):**
**When implementation differences are accounted for**
**One uses ********(2********) to set the free parameter**
**Recent shell model numbers are comparable (differ < factor of 2). But these calculations are still evolving.**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## RQRPA* and Shell Model Predictions

- *renormalized quasiparticle random phase approximation

- Factor 2
- in  or 

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Progress in testing the matrix elements

**Rodin *****et al*****. used ********(2********) to set free parameter in QRPA. They found that this removed most of the spread in the ********(0********) QRPA values. ****(nucl-th/0503063)**
**Suhonen showed that this technique for setting g****pp**** predicted poor ******** and ********+**** rates. He advocates using those measurements to set the parameter. ****(nucl-th/0412064)**
**We’ll be watching this productive debate closely.**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## NuSAG Recommendations

**“****Recommendation: The Neutrino Scientific Assessment Group recommends that the highest priority for the first phase of a neutrino-less double beta decay program is to support research in two or more neutrino-less double beta decay experiments to explore the region of degenerate neutrino masses (m********  > 100 meV). The knowledge gained and the technology developed in the first phase should then be used in a second phase to extend the exploration into the inverted hierarchy region of neutrino masses (m******** > 10−20 meV) with a single experiment.”**

**“****Majorana: The excellent background rejection achieved from superior energy resolution in past ****76****Ge experiments must be extended using new techniques. The panel notes with interest the communication between the Majorana and GERDA ****76****Ge experiments which are pursuing different background suppression strategies. The panel supports an experiment of smaller scope than Majorana-180 that will allow verification of the projected performance and achieve scientifically interesting physics sensitivity, including confirmation or refutation of the claimed ****76****Ge signal. A larger ****76****Ge experiment is a good candidate for a larger international collaboration due to the high cost of the enriched isotope.”**

- Steve Elliott, P-25 Seminar

- October 11, 2005

## Summary

**Science:**
***Neutrino mass interest     ***
***Potential for discovery***
***Even null results will be interesting***** **
**Infrastructure:**
***Enrichment availability/Underground facility development***
**Moderate-sized apparatus: **
***Modest footprint***
***No need for large underground cavity***
**Low Risk:**
***Proven technology/ Modular instrument / Re-configurable****** ***
**Experienced and Substantial Collaboration**
***Long neutrino science track record, many technical resources***

- Steve Elliott, P-25 Seminar

- October 11, 2005

## The Majorana Collaboration

*Brown University, Providence, Rhode Island*
- Michael Attisha, Rick Gaitskell, John-Paul Thompson
*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, S. Katulina, Oleg Kochetov, M. Shirchenko,  Yu. Shitov, V. Timkin, T. Vvlov, E. Yakushev, Yu. Yurkowski
*Lawrence Berkeley National Laboratory, Berkeley, California*
- Yuen-Dat Chan, Mario Cromaz, Martina Descovich, Paul Fallon, Brian Fujikawa, Bill Goward, Reyco Henning, Donna Hurley, Kevin Lesko, Paul Luke, Augusto O. Macchiavelli, Akbar Mokhtarani, Alan Poon, Gersende Prior, Al Smith, Craig Tull
*Lawrence Livermore National Laboratory, Livermore, California*
- Dave Campbell, Kai Vetter
*Los Alamos National Laboratory, Los Alamos, New Mexico*
- Mark Boulay, Steven Elliott, Gerry Garvey, Victor M. Gehman, Andrew Green, Andrew Hime, Bill Louis, Gordon McGregor, Dongming Mei, Geoffrey Mills, Larry Rodriguez, Richard Schirato, Richard Van de Water, Hywel White, Jan Wouters
*Oak Ridge National Laboratory, Oak Ridge, Tennessee*
- Cyrus Baktash, Jim Beene, Fred Bertrand, Thomas V. Cianciolo, David Radford, Krzysztof Rykaczewski

*Osaka University, Osaka, Japan*
- Hiroyasu Ejiri, Ryuta Hazama, Masaharu Nomachi
*Pacific Northwest National Laboratory, Richland, Washington*
- Craig Aalseth, Dale Anderson, Richard Arthur, Ronald Brodzinski, Glen Dunham, James Ely, Tom Farmer, Eric Hoppe, David Jordan, Jeremy Kephart, Richard T. Kouzes, Harry Miley, John Orrell, Jim Reeves, Robert Runkle, Bob Schenter, Ray Warner, Glen Warren
*Queen's University, Kingston, Ontario*
- Marie Di Marco, Aksel Hallin, Art McDonald
*Triangle Universities Nuclear Laboratory, Durham, North Carolina and Physics Departments at Duke University and North Carolina State University*
- Henning Back, James Esterline, Mary Kidd, Werner Tornow, Albert Young
*University of Chicago, Chicago, Illinois*
- Juan Collar
*University of South Carolina, Columbia, South Carolina*
- Frank Avignone, Richard Creswick, Horatio A. Farach, Todd Hossbach, George King
*University of Tennessee, Knoxville, Tennessee*
- William Bugg, Yuri Efremenko
*University of Washington, Seattle, Washington*
- John Amsbaugh, Tom Burritt, Jason Detwiler, Peter J. Doe, Joe Formaggio, Mark Howe, Rob Johnson, Kareem Kazkaz, Michael Marino, Sean McGee, Dejan Nilic, R. G. Hamish Robertson, Alexis Schubert, John F. Wilkerson

*Note: Red text indicates students*

- Steve Elliott, P-25 Seminar

- October 11, 2005