A Drabkin-type spin resonator as tunable neutron beam monochromator Piegsa, F.M.; Ries, D.; Filges, U. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2015, Letnik:
794
Journal Article
Recenzirano
A Drabkin-type spin resonator was designed and successfully implemented at the multi-purpose beam line BOA at the spallation neutron source SINQ at the Paul Scherrer Institute. The device selectively ...acts on the magnetic moment of neutrons within an adjustable velocity band and hence can be utilized as a tunable neutron beam monochromator. Several neutron time-of-flight (TOF) spectra have been recorded employing various settings in order to characterize its performance. In a first test application the velocity dependent transmission of a beryllium filter was determined. In addition, we demonstrate that using an exponential current distribution in the spin resonator coil the side-maxima in the TOF spectra usually associated with a Drabkin setup can be strongly suppressed.
The measurement of the incoherent neutron scattering length of the deuteron van den Brandt, B.; Glättli, H.; Hautle, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2009, Letnik:
611, Številka:
2
Journal Article
Recenzirano
The project has the goal to directly determine the bound spin-dependent neutron–deuteron scattering length
b
i
,
d
by measuring the pseudomagnetic precession of polarised cold neutrons passing ...through a target with polarised nuclei. A precise measurement of
b
i
,
d
can be used to increase the accuracy of the only poorly known doublet neutron–deuteron scattering length
b
2
,
d
which is a crucial input parameter for novel effective field theories. We briefly report on the first measurements performed, discuss the systematics and consequent strategies to improve the accuracy of the experiment.
We report on the development of a versatile cryogen-free laboratory cryostat based upon a commercial pulse tube cryocooler. It provides enough cooling power for continuous recondensation of ...circulating 4He gas at a condensation pressure of approximately 250 mbar. Moreover, the cryostat allows for exchange of different cryostat-inserts as well as fast and easy "wet" top-loading of samples directly into the 1 K pot with a turn-over time of less than 75 min. Starting from room temperature and using a 4He cryostat-insert, a base temperature of 1.0 K is reached within approximately seven hours and a cooling power of 250 mW is established at 1.24 K.
A neutron spin polarisation device with a length of only 160
mm and a cross-section of
22
×
34
mm
2
is presented. Its design is specially suited to analyse large beams typically used for radiography ...with polarised cold neutrons. Characterisations show a polarisation efficiency of about 78% and a transmission of 44% for neutrons with a wavelength
λ
of 5
Å. The compact size makes the device versatile and easily implementable for many purposes in neutron physics.
Ultra-low-mass axions are a viable dark matter candidate and may form a coherently oscillating classical field. Nuclear spins in experiments on Earth might couple to this oscillating axion ...dark-matter field, when propagating on Earth’s trajectory through our Galaxy. This spin coupling resembles an oscillating pseudo-magnetic field which modulates the spin precession of nuclear spins. Here we report on the null result of a demonstration experiment searching for a frequency modulation of the free spin-precession signal of 199Hg in a magnetic field. Our search covers the axion mass range
10^{-16} \textrm{eV} \lesssim m_a \lesssim 10^{-13} \textrm{eV}
10
−
16
eV
≲
m
a
≲
10
−
13
eV
and achieves a peak sensitivity to the axion-nucleon coupling of
g_{aNN} \approx 3.5 \times 10^{-6} \textrm{GeV}^{-1}
g
a
N
N
≈
3.5
×
10
−
6
GeV
−
1
.
Neutron spin phase imaging Piegsa, F.M.; van den Brandt, B.; Hautle, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2008, Letnik:
586, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A new neutron imaging technique is proposed, which is based on the position sensitive measurement of the phase shift of neutron spin precession. This phase shift, caused either by magnetic or ...pseudomagnetic fields produced by the investigated object, is measured using a Ramsey-setup for polarised, cold neutrons combined with a ccd-camera commonly used for neutron radiography. The feasibility of the method has been demonstrated in preliminary tests performed at the cold neutron beamline FUNSPIN at Paul Scherrer Institute.
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