-
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;
-
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;
-
M. Agostini,
J. A. Detwiler,
P. Finnerty,
K. Kröninger,
D. Lenz,
J Liu,
M. G. Marino,
R Martin,
K. D. Nguyen,
L. Pandola, A. G. Schubert,
O. Volynets,
P. Zavarise
[show abstract]
[hide abstract]
ABSTRACT: The GERDA and Majorana experiments will search for neutrinoless double-beta
decay of germanium-76 using isotopically enriched high-purity germanium
detectors. Although the experiments differ in conceptual design, they share
many aspects in common, and in particular will employ similar data analysis
techniques. The collaborations are jointly developing a C++ software library,
MGDO, which contains a set of data objects and interfaces to encapsulate, store
and manage physical quantities of interest, such as waveforms and high-purity
germanium detector geometries. These data objects define a common format for
persistent data, whether it is generated by Monte Carlo simulations or an
experimental apparatus, to reduce code duplication and to ease the exchange of
information between detector systems. MGDO also includes general-purpose
analysis tools that can be used for the processing of measured or simulated
digital signals. The MGDO design is based on the Object-Oriented programming
paradigm and is very flexible, allowing for easy extension and customization of
the components. The tools provided by the MGDO libraries are used by both GERDA
and Majorana.
11/2011;
-
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;
-
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;
-
[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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M. Boswell,
Yuen-Dat Chan,
J.A. Detwiler,
P. Finnerty,
R. Henning,
V.M. Gehman,
R.A. Johnson,
D.V. Jordan,
K. Kazkaz,
M. Knapp, [......],
Jing Liu,
Xiang Liu,
S. MacMullin,
M.G. Marino,
A. Mokhtarani,
L. Pandola, A.G. Schubert,
J. Schubert,
C. Tomei,
O. Volynets
[show abstract]
[hide abstract]
ABSTRACT: We describe a physics simulation software framework, MaGe, that is based on the Geant4 simulation toolkit. MaGe is used to simulate the response of ultra-low radioactive background detectors to ionizing radiation, specifically the Majorana and Gerda neutrinoless double-beta decay experiments. Majorana and Gerda use high-purity germanium detectors to search for the neutrinoless double-beta decay of <sup>76</sup>Ge and MaGe is jointly developed between these two collaborations. The MaGe framework contains the geometry models of common objects, prototypes, test stands and the actual experiments. It also implements customized event generators, Geant4 physics lists and output formats. All of these features are available as class libraries that are typically compiled into a single executable. The user selects the particular experimental setup implementation at run-time via macros. The combination of all these common classes into one framework reduces duplication of efforts, eases comparison between simulated data and experiment and simplifies the addition of new detectors to be simulated. This paper focuses on the software framework, custom event generators and physics lists.
IEEE Transactions on Nuclear Science 07/2011; · 1.45 Impact Factor
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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
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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;
-
C E Aalseth,
M Amman,
J F Amsbaugh,
F T Avignone Iii,
H O Back,
A S Barabash,
P S Barbeau,
J R Beene,
M Bergevin,
F E Bertrand, [......],
K Vetter,
R Warner,
J F Wilkerson,
J M Wouters,
E Yakushev,
A R Young,
C.-H Yu,
V Yumatov,
C Zhang,
S Zimmerman
J.L. Orrell. 11/2009; 101111161716(10).
-
V.E. Guiseppe,
C.E. Aalseth,
M. Akashi-Ronquest,
M. Amman,
J.F. Amsbaugh,
F.T. Avignone,
H.O. Back,
A.S. Barabash,
P. Barbeau,
J.R. Beene, [......],
R.L. Varner,
K. Vetter,
R. Warner,
J.F. Wilkerson,
J.M. Wouters,
E. Yakushev,
A.R. Young,
C.-H. Yu,
V. Yumatov,
C. Zhang
[show abstract]
[hide abstract]
ABSTRACT: Neutrinoless double-beta decay searches play a major role in determining the nature of neutrinos, the existence of a lepton violating process, and the effective Majorana neutrino mass. The MAJORANA Collaboration proposes to assemble an array of HPGe detectors to search for neutrinoless double-beta decay in <sup>76</sup>Ge. Our proposed method uses the well-established technique of searching for neutrinoless double-beta decay in high purity Ge-diode radiation detectors that play both roles of source and detector. The technique is augmented with recent improvements in signal processing and detector design, and advances in controlling intrinsic and external backgrounds. Initially, MAJORANA aims to construct a prototype module containing 60 kg of Ge detectors to demonstrate the potential of a future 1-tonne experiment. The design and potential reach of this prototype Demonstrator module will be presented. This paper will also discuss detector optimization and low-background requirements, such as material purity, background rejection, and identification of rare backgrounds required to reach the sensitivity goals of the MAJORANA experiment.
Nuclear Science Symposium Conference Record, 2008. NSS '08. IEEE; 11/2008
-
S R Elliott,
C E Aalseth,
M Akashi-Ronquest,
M Amman,
J F Amsbaugh,
F T Avignone Iii,
H O Back,
C Baktash,
A S Barabash,
P Barbeau, [......],
R L Varner,
K Vetter,
R Warner,
J F Wilkerson,
J M Wouters,
E Yakushev,
A R Young,
C.-H Yu,
V Yumatov,
Z.-B Yin
08/2008;
-
[show abstract]
[hide abstract]
ABSTRACT: Using simulations to understand backgrounds from muon-induced neutrons is important in designing next-generation low-background underground experiments. Validation of relevant physics within the Geant4 simulation package has been completed by comparing to data from two recent experiments. Verification focused on the production and propagation of neutrons at energies important to underground experiments. Discrepancies were observed between experimental data and the simulation. Techniques were explored to correct for these discrepancies.
09/2007;
-
[show abstract]
[hide abstract]
ABSTRACT: To evaluate the onset of spinal anesthesia with power spectral heart rate analysis to determine the influence of the block on the autonomic nervous system.
Prospective, clinical evaluation.
Tertiary-care teaching hospital.
27 ASA physical status I and II patients scheduled for lower extremity orthopedic surgery and free of major cardiac disease or cardiac drugs with direct influence of heart rate (HR) or blood pressure (BP).
Prior to anesthesia, a baseline power spectral heart rate reading was taken in the supine position. Spinal anesthesia was established in the sitting position with 15 mg of bupivacaine and 0.2 mg epinephrine introduced at the L3-L4 interspace with a 22-gauge Quincke needle. The patient was returned supine, and power spectral heart rate data were again collected at 5-minute intervals throughout the procedure. Level of the spinal block was checked at 5-minute intervals until 30 minutes and considered complete when two consecutive readings were unchanged.
Heart rate and BP were recorded at baseline and at five-minute intervals after injection. Power spectral heart rate data included low-frequency activity (LFa), high-frequency activity (HFa), and the ratio (LFa/HFa). Spinal level achieved was recorded by thoracic dermatome at complete onset. Heart rate and BP remained within 20% of control in all cases. Complete onset of the spinal block was present by 30 minutes in all cases. The average level of spinal anesthesia was T8. Compared with baseline, LFa activity decreased, HFa activity remained unchanged, and the ratio was decreased. During endoprosthesis insertion, 9 of 14 total hip patients had a transient ten-fold increase in LFa activity, without HFa change, and a corresponding increase in the ratio.
Power spectral heart rate analysis during low thoracic bupivacaine spinal anesthesia is compatible with decreased sympathetic activity during stable hemodynamic intervals. Insertion of hip endoprosthesis resulted in a dramatic, transient increase in sympathetic activity, indicating that sympathetic activation was still possible despite the presence of surgical anesthesia from the subarachnoid block.
Journal of Clinical Anesthesia 04/1998; 10(2):133-6. · 1.21 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Using simulations to understand backgrounds from muon-induced neutrons is important in designing next-generation low-background underground experiments. Validation of relevant physics within the Geant4 simulation package has been completed by comparing to data from two recent experiments. Verification focused on the production and propagation of neutrons at energies important to underground experiments. Discrepancies were observed between experimental data and the simulation. Techniques were explored to correct for these discrepancies.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
