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[show abstract]
[hide abstract]
ABSTRACT: The evidence for the observation of the Higgs spin-0-boson as a manifestation
of a scalar field provides the missing corner stone for the standard model of
particles (SM). However, the SM fails to explain the non-visible but
gravitationally active part of the universe. Its nature is unknown but the
confirmation of a scalar Higgs is giving a boost to scalar-field-theories. So
far gravity experiments and observations performed at different distances find
no deviation from Newton's gravity law. Therefore dark energy must possess a
screening mechanism which suppresses the scalar-mediated fifth force. Our line
of attack is a novel gravity experiment with neutrons based on a quantum
interference technique. The spectroscopic measurement of quantum states on
resonances with an external coupling makes this a powerful search for dark
matter and dark energy contributions in the universe. Quantum states in the
gravity potential are intimately related to other scalar field or spin-0-bosons
if they exist. If the reason is that some undiscovered particle interact with a
neutron, this results in a measurable energy shift of quantum states in the
gravity potential, because for neutrons the screening effect is absent. We use
Gravity Resonance Spectroscopy to measure the energy splitting at the highest
level of precision, providing a constraint on any possible new interaction. We
obtain a sensitivity of 10^-14 eV. We set an experimental limit on any fifth
force, in particular on parameter \beta<2x10^9 at n=3 for the scalar chameleon
field, which is improved by a factor of 100 compared to our previous experiment
and five orders of magnitude better than from precision tests of atomic
spectra. The pseudoscalar axion coupling is constrained to gsgp/\hbar
c<3x10^-16 at 20\mu m, which is an improvement by a factor of 30. These results
indicate that gravity is understood at this improved level of precision.
08/2012;
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I. Altarev,
M. Daum,
A. Frei,
E. Gutsmiedl,
G. Hampel,
F. J. Hartmann,
W. Heil,
A. Knecht,
J. V. Kratz, T. Lauer,
M. Meier,
S. Paul,
U. Schmidt,
Y. Sobolev,
N. Wiehl,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: We have determined for the first time the velocity distribution of neutrons from a solid 2H2 ultracold neutron (UCN) source. The spectrum rises sharply above 4.5m/s and has a maximum around 7m/s after transport in
an 8m long guide. The number of neutrons in the UCN velocity range (< 7m/s) may be increased by a factor of two by placing
the experiment 1m above the UCN source level.
European Physical Journal A 04/2012; 37(1):9-14. · 2.19 Impact Factor
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M Burghoff,
A. Schnabel,
G. Ban,
T. Lefort,
Y. Lemiere,
O. Naviliat-Cuncic,
E. Pierre,
G. Quemener,
J. Zejma,
M Kasprzak, [......],
J. Krempel,
B. Lauss,
A. Mtchedlishvili,
P. Schmidt-Wellenburg,
G. Zsigmond,
M. Fertl,
B. Franke,
M. Horras,
K. Kirch,
F. Piegsa
[show abstract]
[hide abstract]
ABSTRACT: A permanent electric dipole moment of fundamental spin-1/2 particles violates
both parity (P) and time re- versal (T) symmetry, and hence, also charge-parity
(CP) symmetry since there is no sign of CPT-violation. The search for a neutron
electric dipole moment (nEDM) probes CP violation within and beyond the Stan-
dard Model. The experiment, set up at the Paul Scherrer Institute (PSI), an
improved, upgraded version of the apparatus which provided the current best
experimental limit, dn < 2.9E-26 ecm (90% C.L.), by the RAL/Sussex/ILL
collaboration: Baker et al., Phys. Rev. Lett. 97, 131801 (2006). In the next
two years we aim to improve the sensitivity of the apparatus to sigma(dn) =
2.6E-27 ecm corresponding to an upper limit of dn < 5E-27 ecm (95% C.L.), in
case for a null result. In parallel the collaboration works on the design of a
new apparatus to further increase the sensitivity to sigma(dn) = 2.6E-28 ecm.
10/2011;
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I. Altarev,
G. Ban,
G. Bison,
K. Bodek,
M Daum,
M. Fertl,
P Fierlinger,
B. Franke,
E. Gutsmiedl,
W Heil, [......],
M. Rebetez,
D. Rebreyend,
S. Roccia,
P. Schmidt-Wellenburg,
N. Severijns,
Yu. Sobolev,
A. Weis,
J. Zejma,
J. Zenner,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: 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 using 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. An
non-zero 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.
09/2010;
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I Altarev,
C A Baker,
G Ban,
G Bison,
K Bodek,
M Daum,
P Fierlinger,
P Geltenbort,
K Green,
M G D van der Grinten, [......],
M Rebetez,
D Rebreyend,
S Roccia,
G Rogel,
N Severijns,
D Shiers,
Yu Sobolev,
A Weis,
J Zejma,
G Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: A clock comparison experiment, analyzing the ratio of spin precession frequencies of stored ultracold neutrons and 199Hg atoms, is reported. No daily variation of this ratio could be found, from which is set an upper limit on the Lorentz invariance violating cosmic anisotropy field b perpendicular < 2 x 10(-20) eV (95% C.L.). This is the first limit for the free neutron. This result is also interpreted as a direct limit on the gravitational dipole moment of the neutron |gn| < 0.3 eV/c2 m from a spin-dependent interaction with the Sun. Analyzing the gravitational interaction with the Earth, based on previous data, yields a more stringent limit |gn| < 3 x 10(-4) eV/c2 m.
Physical Review Letters 08/2009; 103(8):081602. · 7.37 Impact Factor
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I. Altarev,
C A Baker,
G. Ban,
K. Bodek,
M Daum,
P Fierlinger,
P Geltenbort,
K Green,
M. G. D. van der Grinten,
E. Gutsmiedl, [......],
S. Roccia,
G. Rogel,
N. Severijns,
D Shiers,
Yu. Sobolev,
R. Stoepler,
A. Weis,
J. Zejma,
J. Zenner,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: We performed ultracold neutron (UCN) storage measurements to search for additional losses due to neutron (n) to mirror-neutron (n') oscillations as a function of an applied magnetic field B. In the presence of a mirror magnetic field B', UCN losses would be maximal for B = B'. We did not observe any indication for nn' oscillations and placed a lower limit on the oscillation time of tau_{nn'} > 12.0 s at 95% C.L. for any B' between 0 and 12.5 uT. Comment: 4 pages, 2 figures. Accepted for publication in Phys. Rev. D
05/2009;
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M Kuźniak,
I. Altarev,
G. Ban,
G. Bison,
K. Bodek,
M Burghoff,
M Daum,
K Eberhardt,
P Fierlinger,
E. Gutsmiedl, [......],
A. Schnabel,
N. Severijns,
Yu. Sobolev,
R. Stoepler,
L Trahms,
M. Tur,
A. Weis,
N. Wiehl,
J. Zejma,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: A new measurement of the neutron EDM, using Ramsey's method of separated oscillatory fields, is in preparation at the new high intensity source of ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland (PSI). The existence of a non-zero nEDM would violate both parity and time reversal symmetry and, given the CPT theorem, might lead to a discovery of new CP violating mechanisms. Already the current upper limit for the nEDM (|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model. The new experiment aims at a two orders of magnitude reduction of the experimental uncertainty, to be achieved mainly by (1) the higher UCN flux provided by the new PSI source, (2) better magnetic field control with improved magnetometry and (3) a double chamber configuration with opposite electric field directions. The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL group's apparatus (which has produced the current best result) moved from Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further step with a new spectrometer, presently in the design phase.
07/2008;
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I Altarev,
F Atchison,
M Daum,
A Frei,
E Gutsmiedl,
G Hampel,
F J Hartmann,
W Heil,
A Knecht,
J V Kratz, T Lauer,
M Meier,
S Paul,
Y Sobolev,
N Wiehl
[show abstract]
[hide abstract]
ABSTRACT: We have measured the acceleration of neutrons by the material optical potential of solid 2H2. Using a gravitational spectrometer, we find a minimal kinetic energy Ec = (99+/-7) neV of neutrons from a superthermal ultracold neutron (UCN) source with solid 2H2 as an UCN converter. The result is in excellent agreement with theoretical predictions, Ec = 106 neV.
Physical Review Letters 02/2008; 100(1):014801. · 7.37 Impact Factor
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I. Altarev,
C A Baker,
G. Ban,
Georg Bison,
K. Bodek,
M Daum,
P Fierlinger,
P Geltenbort,
K Green,
M. G. D. van der Grinten, [......],
Martin Rebetez,
D. Rebreyend,
S. Roccia,
G. Rogel,
N. Severijns,
D Shiers,
Yu. Sobolev,
Antoine Weis,
J. Zejma,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: A clock comparison experiment, analyzing the ratio of spin precession frequencies of stored ultracold neutrons and ¹⁹⁹Hg atoms, is reported. No daily variation of this ratio could be found, from which is set an upper limit on the Lorentz invariance violating cosmic anisotropy field b <sub>⊥</sub><2×10⁻²⁰ eV (95% C.L.). This is the first limit for the free neutron. This result is also interpreted as a direct limit on the gravitational dipole moment of the neutron | g <sub> n </sub>|<0.3 eV/ c ² m from a spin-dependent interaction with the Sun. Analyzing the gravitational interaction with the Earth, based on previous data, yields a more stringent limit | g <sub> n </sub>|<3×10⁻⁴ eV/ c ² m
-
I. Altarev,
CA Baker,
G. Ban,
G. Bison,
K. Bodek,
M Daum,
P Fierlinger,
P Geltenbort,
K Green,
MGD van der Grinten, [......],
M. Rebetez,
D. Rebreyend,
S. Roccia,
G. Rogel,
N. Severijns,
D Shiers,
Y Sobolev,
A. Weis,
J. Zejma,
G. Zsigmond
-
I. Altarev,
C A Baker,
G. Ban,
K. Bodek,
M Daum,
P Fierlinger,
P Geltenbort,
K Green,
M. G. D. van der Grinten,
E. Gutsmiedl, [......],
S. Roccia,
G. Rogel,
N. Severijns,
D Shiers,
Yu. Sobolev,
R. Stoepler,
Antoine Weis,
J. Zejma,
J. Zenner,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: We performed ultracold neutron storage measurements to search for additional losses due to neutron ( n ) to mirror-neutron ( n <sup>'</sup>) oscillations as a function of an applied magnetic field B . In the presence of a mirror magnetic field B <sup>'</sup>, ultracold neutron losses would be maximal for B ~ B <sup>'</sup>. We did not observe any indication for n n <sup>'</sup> oscillations and placed a lower limit on the oscillation time of tau<sub> n n <sup>'</sup>>12.0 s at 95% C.L. for any B <sup>'</sup> between 0 and 12.5 µ T.
-
M. Daum,
P. Fierlinger,
B. Franke,
P. Geltenbort,
L. Goeltl,
E. Gutsmiedl,
J. Karch,
G. Kessler,
K. Kirch,
H.-C. Koch,
A. Kraft, T. Lauer,
B. Lauss,
E. Pierre,
G. Pignol,
D. Reggiani,
P. Schmidt-Wellenburg,
Yu. Sobolev,
T. Zechlau,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: Ultracold neutrons were stored in a volume, using a magnetic dipole field shutter. Radial confinement was provided by material walls. Low-field seeking neutrons were axially confined above the magnetic field. High-field seeking neutrons are trapped inside the magnetic field. They can systematically shift the measured neutron lifetime to lower values in experiments with magnetic confinement.
Physics Letters B. 704(5):456-460.
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I. Altarev,
G. Ban,
G. Bison,
K. Bodek,
M. Daum,
M. Fertl,
P. Fierlinger,
B. Franke,
E. Gutsmiedl,
W. Heil, [......],
M. Rebetez,
D. Rebreyend,
S. Roccia,
P. Schmidt-Wellenburg,
N. Severijns,
Yu. Sobolev,
A. Weis,
J. Zejma,
J. Zenner,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: 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.
Physica B: Condensed Matter.
-
I. Altarev,
G. Ban,
G. Bison,
K. Bodek,
M. Burghoff,
M. Cvijovic,
M. Daum,
P. Fierlinger,
E. Gutsmiedl,
G. Hampel, [......],
T. Sander-Thoemmes,
A. Schnabel,
N. Severijns,
Yu. Sobolev,
R. Stoepler,
L. Trahms,
A. Weis,
N. Wiehl,
J. Zejma,
G. Zsigmond
[show abstract]
[hide abstract]
ABSTRACT: The effort towards a new measurement of the neutron electric dipole moment (nEDM) at the Paul Scherrer Institut's (PSI) new high intensity source of ultracold neutrons (UCN) is described. The experimental technique relies on Ramsey's method of separated oscillatory fields, using UCN in vacuum with the apparatus at ambient temperature. In the first phase, R&D towards the upgrade of the RAL/Sussex/ILL apparatus is being performed at the Institut Laue-Langevin (ILL). In the second phase the apparatus, moved from ILL to PSI, will allow an improvement in experimental sensitivity by a factor of 5. In the third phase, a new spectrometer should gain another order of magnitude in sensitivity. The improvements will be mainly due to (1) much higher UCN intensity, (2) improved magnetometry and magnetic field control, and (3) a double chamber configuration with opposite electric field directions.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
