First results are presented from an experiment that aims at the simultaneous determination of both transversal polarization components of electrons emitted in the decay of free neutrons—two ...observables that have never before been addressed experimentally. A non-zero value of the
R correlation coefficient, due to the
e
-
polarization component perpendicular to the plane spanned by the spin of the decaying neutron and the electron momentum, would signal a violation of time reversal invariance. The value of the
N correlation coefficient, given by the transverse
e
-
polarization component within that plane, is expected to be finite. The measurement of
N, both, probes the Standard Model and serves as an important systematic check of the experimental apparatus with respect to the
R correlation measurement. Data taking using the polarized cold neutron beam FUNSPIN from the SINQ spallation source at the Paul Scherrer Institute, Villigen, Switzerland, has been completed. Preliminary results of the data analysis are presented. Two options for a possible future experiment leading to the accuracy of about
3
×
10
-
4
are discussed.
One of the most important goals of modern nuclear physics is to contruct nuclear force model which properly describes the experimental data. To develop and test predictions of current models the ...breakup super(1)H(d,p p)n reaction was investigated experimentally at 100 and 130 MeV deuteron beam energies. Rich set of data for cross section, vector and tensor analyzing powers was obtained with the use of the SALAD and BINA detectors at KVI and Germanium Wall setup at FZ-Julich. Results are compared with various theoretical approaches which describe the three-nucleon (3N) system dynamics. For correct description of the cross section data both, three-nucleon force (3NF) and Coulomb force, have to be included into calculations and influence of those ingredients is seizable at specific parts of the phase space. In case of the vector analyzing powers very low sensitivity to any effects beyond nucleon-nucleon interaction was found. At 130 MeV, the Axy data are not correctly described when 3NF models are included into calculations.
Precise and large sets of cross section, vector
A
x
,
A
y
and tensor
A
xx
,
A
xy
,
A
yy
analyzing power data for the
1
H
(
d
,
pp
)
n
breakup reactions were measured at 100 and 130 MeV deuteron ...beam energies with the SALAD and BINA detectors at KVI and the Germanium Wall setup at FZ-Jülich. Results are compared with various theoretical approaches which model the three-nucleon system dynamics. The cross section data reveal a sizable three-nucleon force (3NF) and Coulomb force influence. In case of the analyzing powers very low sensitivity to these effects was found and the data are well describe by 2N models only. For
A
xy
at 130 MeV, serious disagreements were observed when 3NF models are included in the calculations.
High-precision tensor analyzing power T
20
data of the
1
H (
d
,pp)n reaction at 130MeV beam energy have been determined for 81 kinematical configurations. They are compared to theoretical ...predictions based on various approaches to describe the dynamics of the three-nucleon (3N) system. The calculations are performed using modern realistic nucleon-nucleon potentials combined with three-nucleon force (3NF) models or with an effective 3NF resulting from the explicit treatment of the
-isobar in coupled-channels (CC) calculations. Alternatively, the framework of chiral perturbation theory is used to generate consistent two-nucleon and three-nucleon potentials at the currently numerically attainable order. Results of the CC calculations with the
degrees of freedom and including long-range Coulomb force are also shown. In general all predictions are consistent with each other and describe the experimental T
20
results quite well. In a few configurations small inconsistencies between the data and the results of all approaches are observed. Predicted effects of the 3NF are not big and in most cases do not lead to an improved description of the data. The Coulomb force effects are also small in size and often opposite to the effects of TM99 3NF.
FUNSPIN polarized cold-neutron beam at PSI Zejma, J.; Ban, G.; Beck, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2005, Letnik:
539, Številka:
3
Journal Article
Recenzirano
Properties of the cold-neutron beam at the FUNSPIN facility of the SINQ neutron source of the Paul Scherrer Institute, Villigen, Switzerland were investigated. The measured flux density
Φ
=
(
2.46
±
...0.04
)
×
10
8
cm
2
s
mA
-
1
, the wavelength averaged mean polarization around the beam axis
P
A
=
(
95.29
±
0.04
)
%
and the mean polarization over the full beam cross-section
P
=
89.75
±
0.01
(
stat
)
±
1.0
(
syst
)
%
are the main attributes of this powerful facility for fundamental particle physics experiments with slow neutrons.
This paper presents the design and implementation of the front-end electronics and the data acquisition (DAQ) system for readout of multi-wire drift chambers (MWDC). Apart of the conventional drift ...time measurement the system delivers the hit position along the wire utilizing the charge division technique. The system consists of preamplifiers, and analog and digital boards sending data to a back-end computer via an Ethernet interface. The data logging software formats the received data and enables an easy access to the data analysis software. The use of specially designed preamplifiers and peak detectors allows the charge-division readout of the low resistance signal wire. The implication of the charge-division circuitry onto the drift time measurement was studied and the overall performance of the electronic system was evaluated in dedicated off-line tests.
Physics at the Planck scale could be revealed by looking for tiny violations of fundamental symmetries in low energy experiments. In 2008, a sensitive test of the isotropy of the universe has been ...performed with stored ultracold neutrons (UCN), this is the first clock-comparison experiment performed with free neutrons. During several days we monitored the Larmor frequency of neutron spins in a weak magnetic field using the Ramsey resonance technique. A nonzero cosmic axial field, violating rotational symmetry, would induce a daily variation of the precession frequency. Our null result constitutes one of the most stringent tests of Lorentz invariance to date.
Precise and large set of cross sections, vector
A
x
,
A
y
and tensor
A
xx
,
A
xy
,
A
yy
analyzing powers for the
1
H
(
d
,
pp
)
n
breakup reactions were measured at 100 and 130 MeV deuteron beam ...energies with the use of the SALAD and BINA detectors at KVI and Germanium Wall setup at FZ-Jülich. Results are compared with various theoretical approaches which model the three-nucleon (3N) system dynamics. The calculations are based on different two-nucleon (2N) potentials which can be combined with models of the three-nucleon force (3NF) and other pieces of the dynamics can also be included like the Coulomb interaction and relativistic effects. The cross sections data reveal seizable 3NF and Coulomb force influence. In case of analyzing powers very low sensitivity to the effects was found and the data are well describe by 2N models only. At 130 MeV for
A
xy
serious disagreements appear when 3NF models are included into calculations.
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