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F. Atchison,
B. Blau,
K. Bodek,
B. van den Brandt,
T. Bryś,
M. Daum,
P. Fierlinger,
P. Geltenbort,
P. Hautle,
R. Henneck, [......],
C.-Y. Liu,
A. Pichlmaier,
C. Plonka,
Y. Pokotilovski,
A. Saunders,
D. Tortorella,
M. Wohlmuther,
A. R. Young,
J. Zejma,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: Ultracold neutrons (UCN) have been produced using the cold neutron (CN) beam FUNSPIN at SINQ on cryogenic oxygen (O2), tetradeuteromethane (C2H4), and deuterium (2H2) targets. The target cell (40 mm long, fiducial volume about 45 cm3) was operated between room temperature and 8 K and UCN were produced from gaseous, liquid and solid targets. UCN rates have been measured as a convolution of UCN production and transport out of the target and to the detector. At least within the accessible temperature range of this experiment, deuterium outperforms the other materials.
EPL (Europhysics Letters) 06/2011; 95(1):12001. · 2.17 Impact Factor
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F Atchison,
B Blau,
K Bodek,
B van den Brandt,
T Bryś,
M Daum,
P Fierlinger,
A Frei,
P Geltenbort,
P Hautle, [......],
A Pichlmaier,
C Plonka,
Y Pokotilovski,
A Saunders,
Y Shin,
D Tortorella,
M Wohlmuther,
A R Young,
J Zejma,
G Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: A measurement of the production of ultracold neutrons from velocity-selected cold neutrons on gaseous and solid deuterium targets is reported. The expected energy dependence for two-particle collisions with well defined neutron and Maxwell-Boltzmann distributed molecular velocities is found for the gas target. The solid target data agree in shape with the phonon density-of-states curve and provide strong evidence for the phonon model including multiphonon excitations.
Physical Review Letters 01/2008; 99(26):262502. · 7.37 Impact Factor
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F. Atchison,
T. Bryś,
M. Daum,
P. Fierlinger,
P. Geltenbort,
R. Henneck, S. Heule,
M. Kasprzak,
K. Kirch,
A. Pichlmaier,
C. Plonka,
U. Straumann,
C. Wermelinger,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: The storage of ultracold neutrons (UCN) in a combined magnetic, gravitational, and material trap is described. Wall materials investigated were diamondlike carbon (DLC) coatings on solid and flexible foil substrates as well as beryllium coatings on solid substrates. The loss coefficient per wall collision, η, and the depolarization probability β were measured simultaneously as a function of temperature (from 70 to 400 K) and energy (from 30 to 80 neV). The results at 70 K are η=(0.7±0.1)×10-4,β=(15.4±1.0)×10-6 for DLC on polyethyleneterephtalate (PET) foil and η=(1.7±0.1)×10-4,β=(0.7±0.3)×10-6 for DLC on aluminum foil. At room temperature the loss coefficients are larger by a factor of about 2 whereas the depolarization probabilities are found to be independent of temperature. The corresponding values for Be at room temperature are η~5×10-4,β~10×10-6. The DLC results for β and for the temperature-dependent part of the loss coefficient, ηT, are interpreted in terms of incoherent scattering by hydrogen. The hydrogen admixture was measured independently by elastic recoil detection analysis to be about 1×1016 atoms/cm2. The data do not support the hypothesis of hydrogen being chemically bound within the top layers of the DLC. Using two different models with a thin waterlike film on top of the substrate we obtain consistency between the temperature-dependent loss contribution and the measured hydrogen contamination.
Phys. Rev. C. 10/2007; 76(4).
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G Ban,
K Bodek,
M Daum,
R Henneck, S Heule,
M Kasprzak,
N Khomutov,
K Kirch,
S Kistryn,
A Knecht, [......],
C Plonka,
G Quéméner,
M Rebetez,
D Rebreyend,
S Roccia,
G Rogel,
M Tur,
A Weis,
J Zejma,
G Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: In case a mirror world with a copy of our ordinary particle spectrum would exist, the neutron n and its degenerate partner, the mirror neutron n', could potentially mix and undergo nn' oscillations. The interaction of an ordinary magnetic field with the ordinary neutron would lift the degeneracy between the mirror partners, diminish the n' amplitude in the n wave function and, thus, suppress its observability. We report an experimental comparison of ultracold neutron storage in a trap with and without superimposed magnetic field. No influence of the magnetic field is found and, assuming negligible mirror magnetic fields, a limit on the oscillation time taunn' > 103 s (95% C.L.) is derived.
Physical Review Letters 10/2007; 99(16):161603. · 7.37 Impact Factor
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S. Heule,
F. Atchison,
M. Daum,
A. Foelske,
R. Henneck,
M. Kasprzak,
K. Kirch,
A. Knecht,
M. Kuźniak,
T. Lippert,
M. Meier,
A. Pichlmaier,
U. Straumann
Applied Surface Science. 01/2007; 253:8245-8249.
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F. Atchison,
T. Bryś,
M. Daum,
P. Fierlinger,
A. Foelske,
M. Gupta,
R. Henneck, S. Heule,
M. Kasprzak,
K. Kirch,
R. Kötz,
M. Kuźniak,
T. Lippert,
C.-F. Meyer,
F. Nolting,
A. Pichlmaier,
D. Schneider,
B. Schultrich,
P. Siemroth,
U. Straumann
Diamond and Related Materials. 01/2007; 16:334-341.
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F. Atchison,
T. Brys,
M. Daum,
P. Fierlinger,
A. Foelske,
M. Gupta,
R. Henneck, S. Heule,
M. Kasprzak,
K. Kirch,
R. Kötz,
M. Kuzniak,
T. Lippert,
C. F. Meyer,
F. Nolting,
A. Pichlmaier,
D. Schneider,
P. Siemroth,
U. Straumann
[show abstract]
[hide abstract]
ABSTRACT: We have produced hydrogen-free diamond-like carbon (DLC) films by vacuum arc deposition for use as wall coating material in ultracold neutron (UCN) applications. The sp3 fraction, the main quality factor for DLC used in UCN applications, was varied from 0.4 to 0.9, the coating thickness between 10 nm and 120 nm. The samples were characterized by using X-ray Absorption Near-Edge Spectroscopy (XANES), X-ray induced Photoelectron Spectroscopy (XPS), Laser induced surface Acoustic Waves (LAwave), cold neutron reflectometry and Raman spectroscopy at visible excitation wavelength. We observe reasonable agreement between the different results for film thicknesses below 20 nm. For larger thickness, we find that the surface-sensitive methods XPS and XANES yield smaller sp3 fractions (by up to 20%) than the bulk-sensitive LAwave, being consistent with the assumption of a lower-density surface layer on a nominal-density bulk layer.
Diamond and Related Materials 01/2007; 16(2):334–341. · 1.91 Impact Factor
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G. Ban,
K. Bodek,
M. Daum,
R. Henneck, S. Heule,
M. Kasprzak,
N. Khomytov,
K. Kirch,
A. Knecht,
S. Kistryn, [......],
A. Pichlmaier,
C. Plonka,
G. Quémener,
M. Rebetez,
D. Rebreyend,
G. Rogel,
B. M. Sabirov,
M. Tur,
A. Weis,
J. Zejma
[show abstract]
[hide abstract]
ABSTRACT: Precision measurements of particle electric dipole moments (EDMs) provide extremely sensitive means to search for non-standard
mechanisms of T (or CP) violation. For the neutron EDM, the upper limit has been reduced by eight orders of magnitude in 50years
thereby excluding several CP violation scenarios. We report here on a new effort aiming at improving the neutron EDM limit
by two orders of magnitude, down to a level of 3 × 10−28e·cm. The two central elements of the approach are the use of the higher densities which will be available at the new dedicated
spallation UCN source at the Paul Scherrer Institute, and the optimization of the in-vacuum Ramsey resonance technique, with
storage chambers at room temperature, to reach new limits of sensitivity.
Hyperfine Interactions 08/2006; 172(1):41-43. · 0.21 Impact Factor
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F. Atchison,
B. Blau,
M. Daum,
P. Fierlinger,
A. Foelske,
P. Geltenbort,
M. Gupta,
R. Henneck, S. Heule,
M. Kasprzak,
M. Kuźniak,
K. Kirch,
M. Meier,
A. Pichlmaier,
Ch. Plonka,
R. Reiser,
B. Theiler,
O. Zimmer,
G. Zsigmond
Physics Letters B. 01/2006; 642:24-27.
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F Atchison,
B Blau,
B van den Brandt,
T Bryś,
M Daum,
P Fierlinger,
P Hautle,
R Henneck, S Heule,
K Kirch,
J Kohlbrecher,
G Kühne,
J A Konter,
A Pichlmaier,
A Wokaun,
K Bodek,
M Kasprzak,
M Kuźniak,
P Geltenbort,
J Zmeskal
[show abstract]
[hide abstract]
ABSTRACT: The total scattering cross sections for slow neutrons with energies in the range 100 neV to 3 meV for solid ortho-2H2 at 18 and 5 K, frozen from the liquid, have been measured. The 18 K cross sections are found to be in excellent agreement with theoretical expectations and for ultracold neutrons dominated by thermal up scattering. At 5 K the total scattering cross sections are found to be dominated by the crystal defects originating in temperature induced stress but not deteriorated by temperature cycles between 5 and 10 K.
Physical Review Letters 11/2005; 95(18):182502. · 7.37 Impact Factor
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T Brysá,
M Daum,
P Fierlinger,
P Geltenbort,
D George,
M Gupta,
R Henneck, S Heule,
M Horvat,
M Kasprzak,
K Kirch,
K Kohlik,
M Negrazus,
A Pichlmaier,
U Straumann,
V Vrankovic,
C Wermelinger
[show abstract]
[hide abstract]
ABSTRACT: We have built a novel apparatus for the investigation of materials for the storage of ultracold neutrons. Neutrons are filled into a storage volume, confined at the bottom by a magnetic field, at the top by gravity and at the sides by the slit-less sample surface under investigation. For different beryllium and diamond-like carbon samples, storage times up to 200 s were obtained at room temperature. The corresponding loss parameters Z for ultracold neutrons varied between 4.2 and 6:8 Â 10 À4 per wall collision. r 2005 Published by Elsevier B.V.
Nuclear Instruments and Methods in Physics Research A. 01/2005; 5502055(55).
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T. Brys,
M. Daum,
P. Fierlinger,
A. Foelske,
M. Gupta,
R. Henneck, S. Heule,
M. Kasprzak,
K. Kirch,
M. Kuzniak,
T. Lippert,
M. Meier,
A. Pichlmaier,
U. Straumann
[show abstract]
[hide abstract]
ABSTRACT: Diamond-like carbon (DLC) is a promising new wall coating material for use in applications with Ultracold Neutrons (UCN). It can potentially replace the toxic beryllium which has been widely used for the storage and transport of UCN.Our aim is to produce DLC-coated neutron guide tubes of up to 1.2 m length with a Pulsed Laser Deposition (PLD) setup which is currently under construction. In order to find optimal process parameters and appropriate settings for the tube coating facility, we are carrying out a research program which includes the production and characterization of DLC films on small test samples.The characterization of the test samples is done by Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and Neutron Reflectometry. We report on first results from the test samples with sp3 fractions up to 55% and give an overview of the tube coating setup.
Diamond and Related Materials. 01/2001;
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F. Atchison,
T. Bryś,
M. Daum,
P. Fierlinger,
P. Geltenbort,
R. Henneck, S. Heule,
M. Kasprzak,
K. Kirch,
A. Pichlmaier,
C. Plonka,
U. Straumann,
C. Wermelinger
[show abstract]
[hide abstract]
ABSTRACT: For the first time, ultracold neutrons have been stored in a volume formed of foils coated with diamond-like carbon. The coefficients for loss, η, and depolarization, β, per wall collision were determined simultaneously. The results for different samples, η∼10−4 and β∼10−5–10−6, are among the best values measured for high Fermi potential materials without elaborate surface pre-treatment. Thin foil storage material will be widely applicable, e.g., in neutron β-decay studies.
Physics Letters B.
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F. Atchison,
B. Blau,
K. Bodek,
B. van den Brandt,
T. Bryś,
M. Daum,
P. Fierlinger,
A. Frei,
P. Geltenbort,
P. Hautle, [......],
A. Pichlmaier,
C. Plonka,
Y. Pokotilovski,
A. Saunders,
Y. Shin,
D. Tortorella,
M. Wohlmuther,
A.R. Young,
J. Zejma,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: We have investigated the properties of the ultracold neutron converter materials deuterium D2, oxygen O2 and heavy methane CD4 in the temperature range between 8 K and room temperature. The experimental program was performed at the FUNSPIN beamline of the Swiss Spallation Neutron Source (SINQ) at Paul Scherrer Institut (PSI). In this paper the measured cold neutron total cross-sections for D2, O2 and CD4 are presented.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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A. Anghel,
F. Atchison,
B. Blau,
B. van den Brandt,
M. Daum,
R. Doelling,
M. Dubs,
P.-A. Duperrex,
A. Fuchs,
D. George, [......],
W. Wagner,
M. Wohlmuther,
G. Zsigmond,
J. Zuellig,
K. Bodek,
S. Kistryn,
J. Zejma,
P. Geltenbort,
C. Plonka,
S. Grigoriev
[show abstract]
[hide abstract]
ABSTRACT: A new type of ultra-cold neutron (UCN) source based on the spallation process is under construction at PSI. The essential elements are a pulsed proton beam with highest intensity () and a low duty cycle (1%), a lead spallation target, a large D2O moderator and a solid deuterium (sD2) converter system. Spallation neutrons are thermalized in the D2O, further cooled and partially downscattered into the ultra-cold neutron range in the sD2. The expected UCN density is higher than in typical experiments, an increase of almost two orders of magnitude over the best source currently available (at ILL). The new UCN source is expected to come into operation in 2009.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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F Atchison,
M Daum,
R. Henneck, S Heule,
M. Horisberger,
M Kasprzak,
K. Kirch,
A. Knecht,
M. Kużniak,
B. Lauss,
A. Mtchedlishvili,
M. Meier,
G. Petzoldt,
C. Plonka-Spehr,
R. Schelldorfer,
U. Straumann,
G. Zsigmond
http://dx.doi.org/10.1140/epja/i2010-10926-x.
