-
V. Cianciolo,
A. B. Balantekin,
A. Bernstein,
V. Cirigliano,
M. D. Cooper,
D. J. Dean,
S. R. Elliott,
B. W. Filippone,
S. J. Freedman,
G. L. Greene, [......],
B. Plaster,
D. Pocanic,
A. W. P. Poon,
D. C. Radford,
M. J. Ramsey-Musolf, R. G. H. Robertson,
G. Savard,
K. Scholberg,
Y. Semertzidis,
J. F. Wilkerson
[show abstract]
[hide abstract]
ABSTRACT: This White Paper describes recent progress and future opportunities in the
area of fundamental symmetries and neutrinos.
12/2012;
-
P. Finnerty,
E. Aguayo,
M. Amman,
F. T. Avignone. III,
A. S. Barabash,
P. J. Barton,
J. R. Beene,
F. E. Bertrand,
M. Boswell,
V. Brudanin, [......],
V. Timkin,
W. Tornow,
R. L. Varner,
K. Vetter,
K. Vorren,
J. F. Wilkerson,
E. Yakushev,
H. Yaver,
A. R. Young,
C-H. Yu. and. V. Yumatov
[show abstract]
[hide abstract]
ABSTRACT: The MAJORANA DEMONSTRATOR will search for the neutrinoless double-beta decay
of the 76Ge isotope with a mixed array of enriched and natural germanium
detectors. The observation of this rare decay would indicate the neutrino is
its own anti-particle, demonstrate that lepton number is not conserved, and
provide information on the absolute mass-scale of the neutrino. The
DEMONSTRATOR is being assembled at the 4850 foot level of the Sanford
Underground Research Facility in Lead, South Dakota. The array will be
contained in a low-background environment and surrounded by passive and active
shielding. The goals for the DEMONSTRATOR are: demonstrating a background rate
less than 3 t$^{-1}$ y$^{-1}$ in the 4 keV region of interest (ROI) surrounding
the 2039 keV 76Ge endpoint energy; establishing the technology required to
build a tonne-scale germanium based double-beta decay experiment; testing the
recent claim of observation of neutrinoless double-beta decay [H. V.
Klapdor-Kleingrothaus and I. V. Krivosheina, Mod. Phys. Lett. A21, 1547
(2006)]; and performing a direct search for light WIMPs (3-10 GeV).
10/2012;
-
A. Knecht,
Z. T. Alexander,
Y. Bagdasarova,
T. M. Cope,
B. G. Delbridge,
X. Flechard,
A. Garcia,
R. Hong,
E. Lienard,
P. Mueller,
O. Naviliat-Cuncic,
A. S. C. Palmer, R. G. H. Robertson,
D. W. Storm,
H. E. Swanson,
S. Utsuno,
F. Wauters,
W. Williams,
C. Wrede,
D. W. Zumwalt
[show abstract]
[hide abstract]
ABSTRACT: The 6He nucleus is an ideal candidate to study the weak interaction. To this
end we have built a high-intensity source of 6He delivering ~10^10 atoms/s to
experiments. Taking full advantage of that available intensity we have
performed a high-precision measurement of the 6He half-life that directly
probes the axial part of the nuclear Hamiltonian. Currently, we are preparing a
measurement of the beta-neutrino angular correlation in 6He beta decay that
will allow to search for new physics beyond the Standard Model in the form of
tensor currents.
08/2012;
-
The MAJORANA Collaboration,
E. Aguayo,
M. Amman,
F. T. Avignone III,
A. S. Barabash,
P. J. Barton,
J. R. Beene,
F. E. Bertrand,
M. Boswell,
V. Brudanin, [......],
W. Tornow,
R. L. Varner,
K. Vetter,
K. Vorren,
J. F. Wilkerson,
E. Yakushev,
H. Yaver,
A. R. Young,
C. -H. Yu,
V. Yumatov
[show abstract]
[hide abstract]
ABSTRACT: A study of signals originating near the lithium-diffused n+ contact of p-type
point contact (PPC) high purity germanium detectors (HPGe) is presented. The
transition region between the active germanium and the fully dead layer of the
n+ contact is examined. Energy depositions in this transition region are shown
to result in partial charge collection. This provides a mechanism for events
with a well defined energy to contribute to the continuum of the energy
spectrum at lower energies. A novel technique to quantify the contribution from
this source of background is introduced. Experiments that operate germanium
detectors with a very low energy threshold may benefit from the methods
presented herein.
07/2012;
-
K. N. Abazajian,
M. A. Acero,
S. K. Agarwalla,
A. A. Aguilar-Arevalo,
C. H. Albright,
S. Antusch,
C. A. Arguelles,
A. B. Balantekin,
G. Barenboim,
V. Barger, [......],
W. Winter,
Y. Y. Y. Wong,
T. T. Yanagida,
O. Yasuda,
M. Yeh,
F. Yermia,
Z. W. Yokley,
G. P. Zeller,
L. Zhan,
H. Zhang
[show abstract]
[hide abstract]
ABSTRACT: This white paper addresses the hypothesis of light sterile neutrinos based on
recent anomalies observed in neutrino experiments and the latest astrophysical
data.
04/2012;
-
H. Ejiri,
P. Doe,
S. R. Elliott,
J. Engel,
M. Finger,
K. Fushimi,
V. Gehman,
M. Greenfield,
R. Hazama,
P. Kavitov, [......],
G. Shirkov,
A. Sissakian,
A. Titov,
S. Umehara,
V. Vaturin,
V. Voronov,
J. F. Wilkerson,
D. I. Will,
S. Yoshida,
V. Vrba
[show abstract]
[hide abstract]
ABSTRACT: The MOON (Majorana/Mo Observatory Of Neutrinos) project aims at studies of the Majorana nature of the neutrino (ν) and the ν-mass spectrum by spectroscopic experiments of neutrino-less double beta decays (0νββ) with the ν-mass sensitivity of 〈m
ν
m
〉 = 100−30 meV. The solid scintillator option of the MOON detector is a super ensemble of multi-layer modules, each being
composed by PL scintillator plates and position-sensitive detector planes with good overall energy resolution of σ ≈ 2% at the Q
ββ
≈ 3 MeV. Thin ββ source films are interleaved between the detector planes. High localization of the two β tracks enables one to select true signals and reject BG ones. The multi-layer structure of the detector makes it realistic
to build a compact ton-scale detector. MOON with detector ≠ ββ source is used for studying 0νββ decays from 100Mo, 82Se and other ββ isotopes with large Q
ββ
. Real-time exclusive measurements of low energy solar neutrinos can be made by observing inverse β rays from solar-ν captures of 100Mo in delayed coincidence with the subsequent β decay of 100Tc.
The European Physical Journal Special Topics 04/2012; 162(1):239-250. · 1.56 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The Karlsruhe Tritium Neutrino Experiment (KATRIN) will detect tritium beta-
decay electrons that pass through its electromagnetic spectrometer with a
highly- segmented monolithic silicon pin-diode focal-plane detector (FPD). This
pin-diode array will be on a single piece of 500-{\mu}m-thick silicon, with
contact between titanium nitride (TiN) coated detector pixels and front-end
electronics made by spring-loaded pogo pins. The pogo pins will exert a total
force of up to 50N on the detector, deforming it and resulting in mechanical
stress up to 50 MPa in the silicon bulk. We have evaluated a prototype
pin-diode array with a pogo-pin connection scheme similar to the KATRIN FPD. We
find that pogo pins make good electrical contact to TiN and observe no effects
on detector resolution or reverse-bias leakage current which can be attributed
to mechanical stress.
02/2012;
-
D. G. Phillips II,
E. Aguayo,
F. T. Avignone III,
H. O. Back,
A. S. Barabash,
M. Bergevin,
F. E. Bertrand,
M. Boswell,
V. Brudanin,
M. Busch, [......],
R. L. Varner,
K. Vetter,
K. Vorren,
J. F. Wilkerson,
B. A. Wolfe,
E. Yakushev,
A. R. Young,
C. -H. Yu,
V. Yumatov,
C. Zhang
[show abstract]
[hide abstract]
ABSTRACT: The observation of neutrinoless double-beta decay would resolve the Majorana
nature of the neutrino and could provide information on the absolute scale of
the neutrino mass. The initial phase of the Majorana experiment, known as the
Demonstrator, will house 40 kg of Ge in an ultra-low background shielded
environment at the 4850' level of the Sanford Underground Laboratory in Lead,
SD. The objective of the Demonstrator is to determine whether a future 1-tonne
experiment can achieve a background goal of one count per tonne-year in a
narrow region of interest around the 76Ge neutrinoless double-beta decay peak.
11/2011;
-
E. Aguayo,
J. E. Fast,
E. W. Hoppe,
M. E. Keillor,
J. D. Kephart,
R.T. Kouzes,
B. D. LaFerriere,
J. Merriman,
J. L. Orrell,
N. R. Overman, [......],
V. E. Guiseppe,
C Keller,
D. -M. Mei,
G. Perumpilly,
K. Thomas,
C Zhang,
A. L. Hallin,
K. J. Keeter,
L. Mizouni,
J. F. Wilkerson
[show abstract]
[hide abstract]
ABSTRACT: A brief review of the history and neutrino physics of double beta decay is
given. A description of the MAJORANA DEMONSTRATOR research and development
program including background reduction techniques is presented in some detail.
The application of point contact (PC) detectors to the experiment is discussed,
including the effectiveness of pulse shape analysis. The predicted sensitivity
of a PC detector array enriched to 86% in 76Ge is given.
09/2011;
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A Knecht,
D W Zumwalt,
B G Delbridge,
A García,
G C Harper,
R Hong,
P Uller,
A S C Palmer, R G H Robertson,
H E Swanson,
S Utsuno,
D I Will,
W Williams,
C Wrede
[show abstract]
[hide abstract]
ABSTRACT: We have designed and built a lithium target station for the production of 6 He atoms for fundamental research. The system relies on the reaction 7Li(2H, 3He)6He using a deuteron beam provided by the tandem Van de Graaff accelerator available at the Center for Experimental Nuclear Physics and Astrophysics of the University of Washington, which can reach a maximum intensity and energy of 10 mA and 18 MeV. The extracted intensity of gaseous 6He atoms was measured to be 10^9 atoms/s in a low-background experimental area.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 09/2011; 660:43. · 1.21 Impact Factor
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The MAJORANA Collaboration,
E. Aguayo,
F. T. Avignone III,
H. O. Back,
A. S. Barabash,
M. Bergevin,
F. E. Bertrand,
M. Boswell,
V. Brudanin,
M. Busch, [......],
R. L. Varner,
K. Vetter,
K. Vorren,
J. F. Wilkerson,
B. A. Wolfe,
E. Yakushev,
A. R. Young,
C. -H. Yu,
V. Yumatov,
C. Zhang
[show abstract]
[hide abstract]
ABSTRACT: Neutrinoless double-beta decay experiments can potentially determine the
Majorana or Dirac nature of the neutrino, and aid in understanding the neutrino
absolute mass scale and hierarchy. Future 76Ge-based searches target a
half-life sensitivity of >10^27 y to explore the inverted neutrino mass
hierarchy. Reaching this sensitivity will require a background rate of <1 count
tonne^-1 y^-1 in a 4-keV-wide spectral region of interest surrounding the Q
value of the decay. We investigate the overburden required to reach this
background goal in a tonne-scale experiment with a compact (copper and lead)
shield based on Monte Carlo calculations of cosmic-ray background rates. We
find that, in light of the presently large uncertainties in these types of
calculations, a site with an underground depth >~5200 mwe is required for a
tonne-scale experiment with a compact shield similar to the planned 40-kg
MAJORANA DEMONSTRATOR. The required overburden is highly dependent on the
chosen shielding configuration and could be relaxed significantly if, for
example, a liquid cryogen and water shield, or an active neutron shield were
employed. Operation of the MAJORANA DEMONSTRATOR and GERDA detectors will serve
to reduce the uncertainties on cosmic-ray background rates and will impact the
choice of shielding style and location for a future tonne-scale experiment.
4/2013: The peer review process revealed that one of the veto rejection
factors (the factor-of-4 described on p12) needs to be better established. Our
reevaluation of this parameter to date has not yielded strong support for the
value stated in the manuscript, and we require further study to develop a solid
estimate. This further study will supersede the work described in this
manuscript, and may or may not lead to the same conclusion regarding the ~>5200
mwe requirement for future tonne-scale 76Ge neutrinoless double beta decay
experiments.
09/2011;
-
MAJORANA Collaboration,
A. G. Schubert,
E. Aguayo,
F. T. Avignone III,
H. O. Back,
A. S. Barabash,
M. Bergevin,
F. E. Bertrand,
M. Boswell,
V. Brudanin, [......],
R. L. Varner,
K. Vetter,
K. Vorren,
J. F. Wilkerson,
B. A. Wolfe,
E. Yakushev,
A. R. Young,
C. ?H. Yu,
V. Yumatov,
C. Zhan
[show abstract]
[hide abstract]
ABSTRACT: The observation of neutrinoless double-beta decay would determine whether the
neutrino is a Majorana particle and provide information on the absolute scale
of neutrino mass. The MAJORANA Collaboration is constructing the DEMONSTRATOR,
an array of germanium detectors, to search for neutrinoless double-beta decay
of 76-Ge. The DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be
enriched to 86% in 76-Ge. The DEMONSTRATOR will be deployed deep underground in
an ultra-low-background shielded environment. Operation of the DEMONSTRATOR
aims to determine whether a future tonne-scale germanium experiment can achieve
a background goal of one count per tonne-year in a 4-keV region of interest
around the 76-Ge neutrinoless double-beta decay Q-value of 2039 keV.
09/2011;
-
SNO Collaboration,
B. Aharmim,
S N Ahmed,
A E Anthony,
N. Barros,
E W Beier,
A Bellerive,
B. Beltran,
M. Bergevin,
S D Biller, [......],
P. J. S. Watson,
J Wendland,
N West,
J. F. Wilkerson,
J R Wilson,
J.M. Wouters,
A. Wright,
M Yeh,
F Zhang,
K Zuber
[show abstract]
[hide abstract]
ABSTRACT: We report results from a combined analysis of solar neutrino data from all
phases of the Sudbury Neutrino Observatory. By exploiting particle
identification information obtained from the proportional counters installed
during the third phase, this analysis improved background rejection in that
phase of the experiment. The combined analysis resulted in a total flux of
active neutrino flavors from 8B decays in the Sun of (5.25 \pm
0.16(stat.)+0.11-0.13(syst.))\times10^6 cm^{-2}s^{-1}. A two-flavor neutrino
oscillation analysis yielded \Deltam^2_{21} = (5.6^{+1.9}_{-1.4})\times10^{-5}
eV^2 and tan^2{\theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino
oscillation analysis combining this result with results of all other solar
neutrino experiments and the KamLAND experiment yielded \Deltam^2_{21} =
(7.41^{+0.21}_{-0.19})\times10^{-5} eV^2, tan^2{\theta}_{12} =
0.446^{+0.030}_{-0.029}, and sin^2{\theta}_{13} =
(2.5^{+1.8}_{-1.5})\times10^{-2}. This implied an upper bound of
sin^2{\theta}_{13} < 0.053 at the 95% confidence level (C.L.).
09/2011;
-
[show abstract]
[hide abstract]
ABSTRACT: We report results of air monitoring started due to the recent natural catastrophe on 11 March 2011 in Japan and the severe ensuing damage to the Fukushima Dai-ichi nuclear reactor complex. On 17e18 March 2011, we registered the rst arrival of the airborne ssion products 131I, 132I, 132Te, 134Cs, and 137Cs in Seattle, WA, USA, by identifying their characteristic gamma rays using a germanium detector. We measured the evolution of the activities over a period of 23 days at the end of which the activities had mostly fallen below our detection limit. The highest detected activity from radionuclides attached to particulate matter amounted to 4.4 +/- 1.3 mBq/m^3 of 131I on 19-20 March.
Journal of Environmental Radioactivity 07/2011; 102:1032. · 1.34 Impact Factor
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B. Aharmim,
S N Ahmed,
J. F. Amsbaugh,
J. M. Anaya,
A E Anthony,
J. Banar,
N. Barros,
E W Beier,
A Bellerive,
B. Beltran, [......],
J Wendland,
N West,
J.B. Wilhelmy,
J. F. Wilkerson,
J R Wilson,
J.M. Wouters,
A. Wright,
M Yeh,
F Zhang,
K Zuber
[show abstract]
[hide abstract]
ABSTRACT: This paper details the solar neutrino analysis of the 385.17-day Phase-III
data set acquired by the Sudbury Neutrino Observatory (SNO). An array of $^3$He
proportional counters was installed in the heavy-water target to measure
precisely the rate of neutrino-deuteron neutral-current interactions. This
technique to determine the total active $^8$B solar neutrino flux was largely
independent of the methods employed in previous phases. The total flux of
active neutrinos was measured to be
$5.54^{+0.33}_{-0.31}(stat.)^{+0.36}_{-0.34}(syst.)\times 10^{6}$ cm$^{-2}$
s$^{-1}$, consistent with previous measurements and standard solar models. A
global analysis of solar and reactor neutrino mixing parameters yielded the
best-fit values of $\Delta m^2 = 7.59^{+0.19}_{-0.21}\times 10^{-5}{eV}^2$ and
$\theta = 34.4^{+1.3}_{-1.2}$ degrees.
07/2011;
-
B Beltran,
H Bichsel,
B Cai,
G A Cox,
H Deng,
J Detwiler,
J A Formaggio,
S Habib,
A L Hallin,
A Hime, [......],
K Rielage, R G H Robertson,
M W E Smith,
L C Stonehill,
N Tolich,
T Van Wechel,
H Wan Chan Tseung,
J Wendland,
J F Wilkerson,
A Wright
[show abstract]
[hide abstract]
ABSTRACT: The third phase of the Sudbury Neutrino Observatory (SNO) experiment added an array of 3He proportional counters to the detector. The purpose of this neutral-current detection (NCD) array was to observe neutrons resulting from neutral-current solar-neutrino–deuteron interactions. We have developed a detailed simulation of current pulses from NCD array proportional counters, from the primary neutron capture on 3He through NCD array signal-processing electronics. This NCD array MC simulation was used to model the alpha-decay background in SNO's third-phase 8B solar-neutrino measurement.
New Journal of Physics 07/2011; 13(7):073006. · 4.18 Impact Factor
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B. Beltran,
H. Bichsel,
B. Cai,
H Deng,
J. A. Formaggio,
S. Habib,
A. L. Hallin,
A. Hime,
M Huang,
C. Kraus, [......],
K. Rielage, R. G. H. Robertson,
M W E Smith,
L. C. Stonehill,
N Tolich,
T. Van Wechel,
H. Wan Chan Tseung,
J Wendland,
J. F. Wilkerson,
A. Wright
[show abstract]
[hide abstract]
ABSTRACT: The third phase of the Sudbury Neutrino Observatory (SNO) experiment added an
array of 3He proportional counters to the detector. The purpose of this Neutral
Current Detection (NCD) array was to observe neutrons resulting from
neutral-current solar neutrino-deuteron interactions. We have developed a
detailed simulation of the current pulses from the NCD array proportional
counters, from the primary neutron capture on 3He through the NCD array
signal-processing electronics. This NCD array Monte Carlo simulation was used
to model the alpha-decay background in SNO's third-phase 8B solar-neutrino
measurement.
04/2011;
-
H. M. O'Keeffe,
T. H. Burritt,
B. T. Cleveland,
G Doucas,
N Gagnon,
N A Jelley,
C. Kraus,
I T Lawson,
S Majerus,
S. R. McGee,
A. W. Myers,
A. W. P. Poon,
K. Rielage, R. G. H. Robertson,
R. C. Rosten,
L. C. Stonehill,
B. A. VanDevender,
T. D. Van Wechel
[show abstract]
[hide abstract]
ABSTRACT: Four methods for determining the composition of low-level uranium- and
thorium-chain surface contamination are presented. One method is the
observation of Cherenkov light production in water. In two additional methods a
position-sensitive proportional counter surrounding the surface is used to make
both a measurement of the energy spectrum of alpha particle emissions and also
coincidence measurements to derive the thorium-chain content based on the
presence of short-lived isotopes in that decay chain. The fourth method is a
radiochemical technique in which the surface is eluted with a weak acid, the
eluate is concentrated, added to liquid scintillator and assayed by recording
beta-alpha coincidences. These methods were used to characterize two `hotspots'
on the outer surface of one of the He-3 proportional counters in the Neutral
Current Detection array of the Sudbury Neutrino Observatory experiment. The
methods have similar sensitivities, of order tens of ng, to both thorium- and
uranium-chain contamination.
03/2011;
-
C E Aalseth,
E Aguayo,
M Amman,
F T Avignone,
Iii Cd,
H O Back,
X Bai,
A S Barabash,
P S Barbeau,
M Bergevin, [......],
K Vorren,
J F Wilkerson Pf D,
B A Wolfe,
W Xiang,
E Yakushev,
H Yaver,
A R Young,
C.-H Yu,
V Yumatov,
C Zhang
[show abstract]
[hide abstract]
ABSTRACT: The Majorana Collaboration is assembling an array of HPGe detectors to search for neutrinoless double-beta decay in 76Ge. Initially, Majorana aims to construct a prototype module to demonstrate the potential of a future 1-tonne experiment. The design and potential reach of this prototype Demonstrator module are presented.
Nuclear Physics B - Proceedings Supplements 01/2011; 217:44. · 0.88 Impact Factor
-
MAJORANA Collaboration,
C. E. Aalseth,
M. Amman,
F. T. Avignone III,
H. O. Back,
A. S. Barabash,
P. S. Barbeau,
M. Bergevin,
F. E. Bertrand,
M. Boswell, [......],
J. F. Wilkerson,
B. A. Wolfe,
W Xiang,
E. Yakushev,
H. Yaver,
A. R. Young,
C. -H. Yu,
V. Yumatov,
C Zhang,
S. Zimmerman
[show abstract]
[hide abstract]
ABSTRACT: The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg
array of high purity germanium detectors housed in an ultra-low background
shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA
DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while
demonstrating the feasibility of a tonne-scale experiment. It may also carry
out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that
customized Broad Energy Germanium (BEGe) detectors produced by Canberra have
several desirable features for a neutrinoless double-beta decay experiment,
including low electronic noise, excellent pulse shape analysis capabilities,
and simple fabrication. We have deployed a customized BEGe, the MAJORANA
Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and
shield at the Kimballton Underground Research Facility in Virginia. This paper
will focus on the detector characteristics and measurements that can be
performed with such a radiation detector in a low-background environment.
07/2010;
