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UCNA Collaboration,
B. Plaster,
R. Rios,
H. O. Back,
T. J. Bowles,
L. J. Broussard,
R. Carr,
S. Clayton,
S. Currie,
B. W. Filippone, [......],
W. E. Sondheim,
E. Tatar,
B. Tipton,
R. B. Vogelaar,
B. VornDick,
C. Wrede,
Y. P. Xu,
H. Yan,
A. R. Young,
J. Yuan
[show abstract]
[hide abstract]
ABSTRACT: We present a detailed report of a measurement of the neutron
$\beta$-asymmetry parameter $A_0$, the parity-violating angular correlation
between the neutron spin and the decay electron momentum, performed with
polarized ultracold neutrons (UCN). UCN were extracted from a pulsed spallation
solid deuterium source and polarized via transport through a 7-T magnetic
field. The polarized UCN were then transported through an
adiabatic-fast-passage spin-flipper field region, prior to storage in a
cylindrical decay volume situated within a 1-T $2 \times 2\pi$ solenoidal
spectrometer. The asymmetry was extracted from measurements of the decay
electrons in multiwire proportional chamber and plastic scintillator detector
packages located on both ends of the spectrometer. From an analysis of data
acquired during runs in 2008 and 2009, we report $A_0 = -0.11966 \pm
0.00089_{-0.00140} ^{+0.00123}$, from which we extract a value for the ratio of
the weak axial-vector and vector coupling constants of the nucleon, $\lambda =
g_A/g_V = -1.27590 \pm 0.00239_{-0.00377}^{+0.00331}$. Complete details of the
analysis are presented.
07/2012;
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J Liu,
M P Mendenhall,
A T Holley,
H O Back,
T J Bowles,
L J Broussard,
R Carr,
S Clayton,
S Currie,
B W Filippone, [......],
R Russell,
A Saunders,
S J Seestrom,
W E Sondheim,
E Tatar,
R B Vogelaar,
B VornDick,
C Wrede,
H Yan,
A R Young
[show abstract]
[hide abstract]
ABSTRACT: A precise measurement of the neutron decay β asymmetry A₀ has been carried out using polarized ultracold neutrons from the pulsed spallation ultracold neutron source at the Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report A₀ = -0.119 66±0.000 89{-0.001 40}{+0.001 23}, from which we determine the ratio of the axial-vector to vector weak coupling of the nucleon g{A}/g{V}=-1.275 90{-0.004 45}{+0.004 09}.
Physical Review Letters 10/2010; 105(18):181803. · 7.37 Impact Factor
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R W Pattie,
J Anaya,
H O Back,
J G Boissevain,
T J Bowles,
L J Broussard,
R Carr,
D J Clark,
S Currie,
S Du, [......],
E Tatar,
W Teasdale,
C Terai,
B Tipton,
M Utsuro,
R B Vogelaar,
B W Wehring,
Y P Xu,
A R Young,
J Yuan
[show abstract]
[hide abstract]
ABSTRACT: We report the first measurement of an angular correlation parameter in neutron beta decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide and store for approximately 30 s in a Cu decay volume. The interaction of the neutron magnetic dipole moment with a static 7 T field external to the decay volume provides a 420 neV potential energy barrier to the spin state parallel to the field, polarizing the UCN before they pass through an adiabatic fast passage spin flipper and enter a decay volume, situated within a 1 T field in a 2x2pi solenoidal spectrometer. We determine a value for the beta-asymmetry parameter A_{0}=-0.1138+/-0.0046+/-0.0021.
Physical Review Letters 02/2009; 102(1):012301. · 7.37 Impact Factor
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A. Saunders,
J. M. Anaya,
T. J. Bowles,
B. W. Filippone,
P Geltenbort,
R. E. Hill,
M Hino,
S Hoedl, G.E. Hogan,
T. M. Ito, [......],
R. N. Mortensen,
A Pichlmaier,
S. J. Seestrom,
A. Serebrov,
D Smith,
W Teasdale,
B. Tipton,
R. B. Vogelaar,
A. R. Young,
J Yuan
[show abstract]
[hide abstract]
ABSTRACT: Ultra-cold neutrons (UCN), neutrons with energies low enough to be confined by the Fermi potential in material bottles, are playing an increasing role in measurements of fundamental properties of the neutron. The ability to manipulate UCN with material guides and bottles, magnetic fields, and gravity can lead to experiments with lower systematic errors than have been obtained in experiments with cold neutron beams. The UCN densities provided by existing reactor sources limit these experiments. The promise of much higher densities from solid deuterium sources has led to proposed facilities coupled to both reactor and spallation neutron sources. In this paper we report on the performance of a prototype spallation neutron-driven solid deuterium source. This source produced bottled UCN densities of 145 +/-7 UCN/cm3, about three times greater than the largest bottled UCN densities previously reported. These results indicate that a production UCN source with substantially higher densities should be possible.
01/2004;
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[show abstract]
[hide abstract]
ABSTRACT: We have proposed a new method for nuclear material contraband detection based on cosmic ray muon radiography. The method is safe, because it does not include the generation of any artificial radiation, but uses naturally produced high-energy muons. Results obtained with our prototype experiment, and from simulations demonstrate the feasibility of the method for the detection of high-Z materials hidden inside different types of ordinary cargo. Detector technology for muon detection is mature and enables cost-effective design for a muon radiography apparatus. Image reconstruction is not trivial and may be done in various ways. We developed the PoCA algorithm for image reconstruction and the MC (muon crossing) algorithm for the detection of high-Z material. Our simulations of a full-scale muon radiography system suggest high efficiency of detection in 1 minute of exposure with a low number of false positives for a 20 kg of uranium hidden inside 11 tons of uniformly distributed iron.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
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[show abstract]
[hide abstract]
ABSTRACT: Scattering muon radiography is a novel technique of 3-d imaging for dense high-Z objects. High-energy cosmic ray muons are deflected in matter in the process of multiple Coulomb scattering. Measuring the deflection angles we are able to reconstruct the configuration of high-Z material in the object. We discuss how the technique can be used for the detection of compact high-Z objects in a large volume of ordinary material. We present results of our experiments and simulations and discuss image reconstruction issues relevant to scattering muon radiography. The ability of the technique to detect 20 kg of uranium hidden inside more than 10 tons of iron and in less than a minute of exposure is demonstrated.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
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C L Morris,
J M Anaya,
T J Bowles,
B W Filippone,
P Geltenbort,
R E Hill,
M Hino,
S Hoedl, G E Hogan,
T M Ito, [......],
R N Mortensen,
A Pichlmaier,
A Saunders,
S J Seestrom,
D Smith,
W Teasdale,
B Tipton,
M Utsuro,
A R Young,
J Yuan
[show abstract]
[hide abstract]
ABSTRACT: We present the first measurements of the survival time of ultracold neutrons (UCNs) in solid deuterium (SD2). This critical parameter provides a fundamental limitation to the effectiveness of superthermal UCN sources that utilize solid ortho-deuterium as the source material. These measurements are performed utilizing a SD2 source coupled to a spallation source of neutrons, providing a demonstration of UCN production in this geometry and permitting systematic studies of the influence of thermal up-scatter and contamination with para-deuterium on the UCN survival time.
Physical Review Letters 01/2003; 89(27):272501. · 7.37 Impact Factor
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K. Kwiatkowski,
J.-F. Beche,
M.T. Burks,
G. Hart, G.E. Hogan,
P.F. Manfredi,
J.E. Millaud,
C.L. Morris,
N.S.P. King,
P.D. Pazuchanics,
B. Turko
[show abstract]
[hide abstract]
ABSTRACT: We constructed two small-area pixelated detectors, which can
record signals produced by 800-MeV proton beam micropulses with a
repetition rate of 358 ns. The first detector was built around a
two-dimensional (2-D) photodiode array. The array was illuminated by
light emitted by a monolithic 1.7-mm-thick lutetium oxy-orthosilicate
(LSO) scintillator and imaged by a simple optical system. The other
detector was a hydrogen ion chamber operated at 1 to 2.5 atm. The anode
was divided into an array of 8×8 1 mm<sup>2</sup> pixels. The fast
positive-ion drift velocity in hydrogen helps to minimize the space
charge build up. However, for beam pulses spaced in time closer than 1
μs, there appears to be a substantial accumulation of space charge.
The electronic readout chain, for each of the 64 channels, consisted of
an externally clocked fast-gated integrator and an amplifier coupled to
an on-board analog-to-digital converter (ADC) and a first-in-first-out
storage (FIFO). The detectors were tested with beam pulses up to
4×10<sup>6</sup> protons per mm<sup>2</sup> delivered in 30 to 120
ns wide microbursts
IEEE Transactions on Nuclear Science 03/2002; · 1.45 Impact Factor
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K. Kwiatkowski,
J.-F. Beche,
M. Burks,
G. Hart, G.E. Hogan,
F. Manfredi,
J. Millaud,
C.L. Morris,
N.S.P. King,
P.D. Pazuchanics,
A. Saunders,
B. Turko,
H.-J. Ziock,
J.D. Zumbro
[show abstract]
[hide abstract]
ABSTRACT: Two prototype small-area pixilated detectors, capable of recording
signals produced by 800 MeV proton beam micropulses, with a repetition
rate of 358 ns, were constructed. The first detector system was built
around a two-dimensional photodiode array. The array was illuminated by
light emitted by a monolithic 1.7 mm thick LSO scintillator and imaged
by a simple mirror and lens optical system. Tests were carried out with
an array of 8×8 pixels 1 mm<sup>2</sup> in area. The other
detector was a hydrogen ion-chamber operated at 1 to 2.5 atm. The fast
positive-ion drift velocity in hydrogen helps to minimize the space
charge build up. However, for pulses spaced closely in time, less than 1
μs, there appear to be a substantial accumulation of positive space
charge. The electronic readout chain, for each of the 64 channels,
consisted of an externally clocked fast gated integrator and an
amplifier coupled to an on-board ADC and a FIFO. The detectors were
tested with a beam of up to 6×10<sup>6</sup> protons per mm<sup>2
</sup> in 30 to 120 ns-wide microbursts
Nuclear Science Symposium Conference Record, 2000 IEEE; 02/2000
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G.E. Hogan
[show abstract]
[hide abstract]
ABSTRACT: Summary form only given. PC DAQ is a Windows NT based general
DAQ/Analysis/Monte Carlo shell developed as part of the Proton
Radiography project at LANL (Los Alamos National Laboratory). It has
been adopted by experiments outside of the Proton Radiography project at
Brookhaven National Laboratory (BNL) and at LANL. The program provides
DAQ, Monte Carlo, and replay (disk file input) modes. Data can be read
from hardware (CAMAC) or other programs (ActiveX servers) and from
multiple workstations. User supplied data analysis routines can be
written in Fortran, C++, or Visual Basic. Histogramming, testing, and
plotting packages are provided. Histogram data can be exported to
spreadsheets or analyzed in user supplied programs. Plots can be copied
and pasted as bitmap objects into other Windows programs or printed. A
text database keyed by the run number is provided. Extensive software
control flags are provided so that the user can control the flow of data
through the program. Control flags can be set either in script command
files or interactively. The program can be remotely controlled and data
accessed over the Internet through its ActiveX DCOM interface
Real Time Conference, 1999. Santa Fe 1999. 11th IEEE NPSS; 02/1999
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Pattie,
R. W,
J Anaya,
H. O. Back,
J G Boissevain,
T. J. Bowles,
L. J. Broussard,
R Carr,
D. J. Clark,
S Currie, [......],
E Tatar,
W Teasdale,
C Terai,
B. Tipton,
M Utsuro,
R. B. Vogelaar,
B. W. Wehring,
Y. P. Xu,
A. R. Young,
J Yuan
[show abstract]
[hide abstract]
ABSTRACT: We report the first measurement of an angular correlation parameter in neutron β decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide and store for ~30 s in a Cu decay volume. The interaction of the neutron magnetic dipole moment with a static 7 T field external to the decay volume provides a 420 neV potential energy barrier to the spin state parallel to the field, polarizing the UCN before they pass through an adiabatic fast passage spin flipper and enter a decay volume, situated within a 1 T field in a 2×2π solenoidal spectrometer. We determine a value for the β-asymmetry parameter A_0=-0.1138±0.0046±0.0021.
