-
M Auger,
D J Auty,
P S Barbeau,
E Beauchamp,
V Belov,
C Benitez-Medina,
M Breidenbach,
T Brunner,
A Burenkov,
B Cleveland, [......],
J-L Vuilleumier,
A Waite,
T Walton,
M Weber,
U Wichoski,
J Wodin,
J D Wright,
L Yang,
Y-R Yen,
O Ya Zeldovich
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for neutrinoless double-beta decay of 136Xe with EXO-200. No signal is observed for an exposure of 32.5 kg yr, with a background of ∼1.5×10(-3) kg(-1) yr(-1) keV(-1) in the ±1σ region of interest. This sets a lower limit on the half-life of the neutrinoless double-beta decay T(1/2)(0νββ)(136Xe)>1.6×10(25) yr (90% C.L.), corresponding to effective Majorana masses of less than 140-380 meV, depending on the matrix element calculation.
Physical Review Letters 07/2012; 109(3):032505. · 7.37 Impact Factor
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M. Auger,
D. J. Auty,
P. S. Barbeau,
E. Beauchamp,
V. Belov,
C. Benitez-Medina,
M. Breidenbach,
T. Brunner,
A. Burenkov,
B. Cleveland, [......],
J. -L. Vuilleumier,
A. Waite,
T. Walton,
M. Weber,
U. Wichoski,
J. Wodin,
J. D. Wright,
L. Yang,
Y. -R. Yen,
O. Ya. Zeldovich
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for neutrinoless double-beta decay of $^{136}$Xe with
EXO-200. No signal is observed for an exposure of 32.5 kg-yr, with a background
of ~1.5 x 10^{-3} /(kg yr keV) in the $\pm 1\sigma$ region of interest. This
sets a lower limit on the half-life of the neutrinoless double-beta decay
$T_{1/2}^{0\nu\beta\beta}$($^{136}$Xe) > 1.6 x 10$^{25}$ yr (90% CL),
corresponding to effective Majorana masses of less than 140-380 meV, depending
on the matrix element calculation.
05/2012;
-
M. Auger,
D. J. Auty,
P. S. Barbeau,
L. Bartoszek,
E. Baussan,
E. Beauchamp,
C. Benitez-Medina,
M. Breidenbach,
D. Chauhan,
B. Cleveland, [......],
K. Twelker,
J. -L. Vuilleumier,
J. -M. Vuilleumier,
T. Walton,
M. Weber,
U. Wichoski,
J. Wodin,
J. D. Wright,
L. Yang,
Y. -R. Yen
[show abstract]
[hide abstract]
ABSTRACT: EXO-200 is an experiment designed to search for double beta decay of
$^{136}$Xe with a single-phase, liquid xenon detector. It uses an active mass
of 110 kg of xenon enriched to 80.6% in the isotope 136 in an ultra-low
background time projection chamber capable of simultaneous detection of
ionization and scintillation. This paper describes the EXO-200 detector with
particular attention to the most innovative aspects of the design that revolve
around the reduction of backgrounds, the efficient use of the expensive
isotopically enriched xenon, and the optimization of the energy resolution in a
relatively large volume.
02/2012;
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N Ackerman,
B Aharmim,
M Auger,
D J Auty,
P S Barbeau,
K Barry,
L Bartoszek,
E Beauchamp,
V Belov,
C Benitez-Medina, [......],
S Waldman,
T Walton,
K Wamba,
M Weber,
U Wichoski,
J Wodin,
J D Wright,
L Yang,
Y-R Yen,
O Ya Zeldovich
[show abstract]
[hide abstract]
ABSTRACT: We report the observation of two-neutrino double-beta decay in (136)Xe with T(1/2) = 2.11 ± 0.04(stat) ± 0.21(syst) × 10(21) yr. This second-order process, predicted by the standard model, has been observed for several nuclei but not for (136)Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.
Physical Review Letters 11/2011; 107(21):212501. · 7.37 Impact Factor
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F LePort,
R Neilson,
P S Barbeau,
K Barry,
L Bartoszek,
I Counts,
J Davis,
R deVoe,
M J Dolinski,
G Gratta, [......],
S Slutsky,
V Stekhanov,
V Strickland,
M Swift,
J-L Vuilleumier,
J-M Vuilleumier,
U Wichoski,
J Wodin,
L Yang,
Y-R Yen
[show abstract]
[hide abstract]
ABSTRACT: A magnetically driven piston pump for xenon gas recirculation is presented. The pump is designed to satisfy extreme purity and containment requirements, as is appropriate for the recirculation of isotopically enriched xenon through the purification system and large liquid xenon time projection chamber of EXO-200. The pump, using sprung polymer gaskets, is capable of pumping more than 16 standard liters per minute of xenon gas with 750 Torr differential pressure.
The Review of scientific instruments 10/2011; 82(10):105114. · 1.52 Impact Factor
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A. Dobi,
C Hall,
S. Slutsky,
Y. -R. Yen,
B. Aharmin,
M. Auger,
P. S. Barbeau,
C. Benitez-Medina,
M Breidenbach,
B. Cleveland, [......],
V. Strickland,
M. Swift,
K. Twelker,
J L Vuilleumier,
J. -M. Vuilleumier,
M Weber,
U. Wichoski,
J. Wodin,
J D Wright,
L. Yang
[show abstract]
[hide abstract]
ABSTRACT: We describe purity measurements of the natural and enriched xenon stockpiles
used by the EXO-200 double beta decay experiment based on a mass spectrometry
technique. The sensitivity of the spectrometer is enhanced by several orders of
magnitude by the presence of a liquid nitrogen cold trap, and many impurity
species of interest can be detected at the level of one part-per-billion or
better. We have used the technique to screen the EXO-200 xenon before, during,
and after its use in our detector, and these measurements have proven useful.
This is the first application of the cold trap mass spectrometry technique to
an operating physics experiment.
09/2011;
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N. Ackerman,
B. Aharmim,
M. Auger,
D. J. Auty,
P. S. Barbeau,
K. Barry,
L. Bartoszek,
E. Beauchamp,
V. Belov,
C. Benitez-Medina, [......],
S. Waldman,
T. Walton,
K. Wamba,
M Weber,
U. Wichoski,
J. Wodin,
J D Wright,
L. Yang,
Y. -R. Yen,
O. Ya. Zeldovich
[show abstract]
[hide abstract]
ABSTRACT: We report the observation of two-neutrino double-beta decay in Xe-136 with
T_1/2 = 2.11 +- 0.04 (stat.) +- 0.21 (sys.) x 10^21 yr. This second order
process, predicted by the Standard Model, has been observed for several nuclei
but not for Xe-136. The observed decay rate provides new input to matrix
element calculations and to the search for the more interesting neutrino-less
double-beta decay, the most sensitive probe for the existence of Majorana
particles and the measurement of the neutrino mass scale.
08/2011;
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D Sinclair,
E Rollin,
J Smith,
A Mommers,
N Ackeran,
B Aharmin,
M Auger,
P S Barbeau,
C Benitez-Medina,
M Breidenbach, [......],
P C Rowson,
S Slutsky,
V Stekhanov,
K Twelker,
N Voskanian,
J -L Vuilleumier,
U Wichoski,
J Wodin,
L Yang,
Y -R Yen
[show abstract]
[hide abstract]
ABSTRACT: Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the Ba++ can be efficiently converted to Ba+ as required for laser identification.
Journal of Physics Conference Series 08/2011; 309(1):012005.
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EXO Collaboration,
A. Dobi,
C Hall,
S. Herrin,
A. Odian, C Y Prescott,
P C Rowson,
N. Ackerman,
B. Aharmin,
M. Auger, [......],
D Sinclair,
S. Slutsky,
V. Stekhanov,
K. Twelker,
N. Voskanian,
J L Vuilleumier,
U. Wichoski,
J. Wodin,
L. Yang,
Y. -R. Yen
[show abstract]
[hide abstract]
ABSTRACT: We discuss the design, operation, and calibration of two versions of a xenon
gas purity monitor (GPM) developed for the EXO double beta decay program. The
devices are sensitive to concentrations of oxygen well below 1 ppb at an
ambient gas pressure of one atmosphere or more. The theory of operation of the
GPM is discussed along with the interactions of oxygen and other impurities
with the GPM's tungsten filament. Lab tests and experiences in commissioning
the EXO-200 double beta decay experiment are described. These devices can also
be used on other noble gases.
06/2011;
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M. Montero Diez,
K. Twelker,
W. Fairbank,
G. Gratta,
P. S. Barbeau,
K. Barry,
R. DeVoe,
M. J. Dolinski,
M. Green,
F. LePort, [......],
E. Rollin,
P. C. Rowson,
D. Sinclair,
S. Slutsky,
V. Stekhanov,
J.-L. Vuilleumier,
U. Wichoski,
J. Wodin,
L. Yang,
Y.-R. Yen
[show abstract]
[hide abstract]
ABSTRACT: We describe a source capable of producing single barium ions through nuclear recoils in radioactive decay. The source is fabricated by electroplating <sup>148</sup> G d onto a silicon α -particle detector and vapor depositing a layer of BaF <sub>2</sub> over it. <sup>144</sup> S m recoils from the alpha decay of <sup>148</sup> G d are used to dislodge Ba <sup>+</sup> ions from the BaF <sub>2</sub> layer and emit them in the surrounding environment. The simultaneous detection of an α particle in the substrate detector allows for tagging of the nuclear decay and of the Ba <sup>+</sup> emission. The source is simple, durable, and can be manipulated and used in different environments. We discuss the fabrication process, which can be easily adapted to emit most other chemical species, and the performance of the source.
Review of Scientific Instruments 12/2010; · 1.37 Impact Factor
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D.S. Leonard,
P. Grinberg,
P. Weber,
E. Baussan,
Z. Djurcic,
G. Keefer,
A. Piepke,
A. Pocar,
J.-L. Vuilleumier,
J.-M. Vuilleumier, [......],
P.C. Rowson,
D. Schenker,
D. Sinclair,
K. Skarpaas,
G. Smirnov,
V. Stekhanov,
V. Strickland,
C. Virtue,
K. Wamba,
J. Wodin
[show abstract]
[hide abstract]
ABSTRACT: The Enriched Xenon Observatory (EXO) will search for double beta decays of 136Xe. We report the results of a systematic study of trace concentrations of radioactive impurities in a wide range of raw materials and finished parts considered for use in the construction of EXO-200, the first stage of the EXO experimental program. Analysis techniques employed, and described here, include direct gamma counting, alpha counting, neutron activation analysis, and high-sensitivity mass spectrometry.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 10/2007;
-
M Green,
J. Wodin,
R. DeVoe,
P. Fierlinger,
B. Flatt,
G. Gratta,
F. LePort,
M. Montero Diez,
R. Neilson,
K. OSullivan, [......],
M Breidenbach,
R. Conley,
C Hall,
J. Hodgson,
D. Mackay,
A. Odian, C Y Prescott,
P C Rowson,
K Skarpaas,
K. Wamba
[show abstract]
[hide abstract]
ABSTRACT: Individual Ba ions are trapped in a gas-filled linear ion trap and observed with a high signal-to-noise ratio by resonance fluorescence. Single-ion storage times of ~5 min (~1 min) are achieved using He (Ar) as a buffer gas at pressures in the range 8e-5 - 4e-3 torr. Trap dynamics in buffer gases are experimentally studied in the simple case of single ions. In particular, the cooling effects of light gases such as He and Ar and the destabilizing properties of heavier gases such as Xe are studied. A simple model is offered to explain the observed phenomenology. Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. A. Minor text and figure changes
02/2007;
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EXO Collaboration: F. LePort,
A. Pocar,
L. Bartoszek,
R. DeVoe,
P. Fierlinger,
B. Flatt,
G. Gratta,
M Green,
T. Koffas,
M. Montero Diez, [......],
K Skarpaas,
D. Schenker,
D Sinclair,
V. Stekhanov,
V. Strickland,
C. Virtue,
J L Vuilleumier,
J. -M. Vuilleumier,
K. Wamba,
P Weber
[show abstract]
[hide abstract]
ABSTRACT: A novel technique has been developed to build vessels for liquid xenon ionization detectors entirely out of ultra-clean fluoropolymer. We describe the advantages in terms of low radioactivity contamination, provide some details of the construction techniques, and show the energy resolution achieved with a prototype all-fluoropolymer ionization detector.
12/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: The GaAsP/GaAs strained superlattice photocathode structure has proven to be a significant advance for polarized electron sources operating with high peak currents per microbunch and relatively low duty factor. This is the characteristic type of operation for SLAC and is also planned for the ILC. This superlattice structure was studied at SLAC [1], and an optimum variation was chosen for the final stage of E-158, a high-energy parity violating experiment at SLAC. Following E-158, the polarized source was maintained on standby with the cathode being re-cesiated about once a week while a thermionic gun, which is installed in parallel with the polarized gun, supplied the linac electron beams. However, in the summer of 2005, while the thermionic gun was disabled, the polarized electron source was again used to provide electron beams for the linac. The performance of the photocathode 24 months after its only activation is described and factors making this possible are discussed.
02/2006
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Koya Abe,
Kenji Abe,
T. Abe,
I. Adam,
H. Akimoto,
D. Aston,
K. G. Baird,
C. Baltay,
H. R. Band,
T. L. Barklow, [......],
R. J. Wilson,
W. J. Wisniewski,
J. L. Wittlin,
M. Woods,
T. R. Wright,
R. K. Yamamoto,
J. Yashima,
S. J. Yellin,
C. C. Young,
H. Yuta
[show abstract]
[hide abstract]
ABSTRACT: We measure the hadronic branching ratios of the Z0 boson into heavy quarks: Rb=ΓZ0→bb̅ /ΓZ0→hadrons and Rc=ΓZ0→cc̅ /ΓZ0→hadrons using a multitag technique. The measurement was performed using about 400 000 hadronic Z0 events recorded in the SLC Large Detector experiment at SLAC between 1996 and 1998. The small and stable SLAC Linear Collider beam spot and the CCD-based vertex detector were used to reconstruct bottom and charm hadron decay vertices with high efficiency and purity, which enables us to measure most efficiencies from data. We obtain, Rb=0.21604±0.00098(stat.)±0.00073(syst.)∓0.00012(Rc) and, Rc=0.1744±0.0031(stat.)±0.0020(syst.)∓0.0006(Rb).
Phys. Rev. D. 06/2005; 71(11).
-
Koya Abe,
Kenji Abe,
T Abe,
I Adam,
H Akimoto,
D Aston,
K G Baird,
C Baltay,
H R Band,
T L Barklow, [......],
R J Wilson,
W J Wisniewski,
J L Wittlin,
M Woods,
T R Wright,
R K Yamamoto,
J Yashima,
S J Yellin,
C C Young,
H Yuta
[show abstract]
[hide abstract]
ABSTRACT: Exploiting the manipulation of the SLAC Linear Collider electron-beam polarization, we present precise direct measurements of the parity-violation parameters A(c) and A(b) in the Z-boson-c-quark and Z-boson-b-quark coupling. Quark-antiquark discrimination is accomplished via a unique algorithm that takes advantage of the precise SLAC Large Detector charge coupled device vertex detector, employing the net charge of displaced vertices as well as the charge of kaons that emanate from those vertices. From the 1996-1998 sample of 400 000 Z decays, produced with an average beam polarization of 73.4%, we find A(c)=0.673+/-0.029(stat)+/-0.023(syst) and A(b)=0.919+/-0.018(stat)+/-0.017(syst).
Physical Review Letters 04/2005; 94(9):091801. · 7.37 Impact Factor
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K. Wamba,
C. Hall,
M. Breidenbach,
R. Conley,
A. Odian, C.Y. Prescott,
P.C. Rowson,
J. Sevilla,
K. Skarpaas,
R. DeVoe, [......],
J.-M. Martin,
R. Neilson,
L. Ounalli,
A. Piepke,
D. Schenker,
V. Stekhanov,
J.-L. Vuilleumier,
S. Waldman,
P. Weber,
J. Wodin
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the 226Th ion mobility in LXe at 163.0 K and 0.9 bar. The result obtained, 0.240±0.011 (stat) ±0.011 (syst) cm2/(kV-s), is compared with a popular model of ion transport.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 03/2005;
-
[show abstract]
[hide abstract]
ABSTRACT: Future electron-positron linear colliders require a highly polarized electron beam with a pulse structure that depends primarily on whether the acceleration utilizes warm or superconducting rf structures. The International Linear Collider (ILC) will use cold structures for the main linac. It is shown that a dc-biased polarized photoelectron source such as successfully used for the SLC can meet the charge requirements for the ILC micropulse with a polarization approaching 90%.
01/2005;
-
[show abstract]
[hide abstract]
ABSTRACT: Atomic hydrogen cleaning followed by heat cleaning at 450$^\circ$C was used to prepare negative-electron-affinity GaAs photocathodes. When hydrogen ions were eliminated, quantum efficiencies of 15% were obtained for bulk GaAs cathodes, higher than the results obtained using conventional 600$^\circ$C heat cleaning. The low-temperature cleaning technique was successfully applied to thin, strained GaAs cathodes used for producing highly polarized electrons. No depolarization was observed even when the optimum cleaning time of about 30 seconds was extended by a factor of 100.
01/2005;
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D. Akimov,
G. Bower,
M. Breidenbach,
R. Conley,
E. Conti,
M. Danilov,
R. Devoe,
Z. Djurcic,
A. Dolgolenko,
W. Fairbank, [......],
A. Piepke, C. Y. Prescott,
P. C. Rowson,
K. Skarpaas,
P. Vogel,
J.-L. Vuilleumier,
S. Waldman,
K. Wamba,
J. Wodin,
O. Zeldovich
Nuclear Physics B - Proceedings Supplements 12/2004; 138:224-226. · 0.88 Impact Factor
