8,411 research outputs found
Search for strange quark matter and Q-balls with the SLIM experiment
We report on the search for Strange Quark Matter (SQM) and charged Q-balls
with the SLIM experiment at the Chacaltaya High Altitude Laboratory (5230 m
a.s.l.) from 2001 to 2005. The SLIM experiment was a 427 m array of
Nuclear Track Detectors (NTDs) arranged in modules of cm
area. SLIM NTDs were exposed to the cosmic radiation for 4.22 years after which
they were brought back to the Bologna Laboratory where they were etched and
analyzed. We estimate the properties and energy losses in matter of nuclearites
(large SQM nuggets), strangelets (small charged SQM nuggets) and Q-balls; and
discuss their detection with the SLIM experiment. The flux upper limits in the
CR of such downgoing particles are at the level of /cm/s/sr
(90% CL).Comment: 4 pages, 7 eps figures. Talk given at the 24th International
Conference on Nuclear Tracks in Solids, Bologna, Italy, 1-5 September 200
Nuclear Track Detectors. Searches for Exotic Particles
We used Nuclear Track Detectors (NTD) CR39 and Makrofol for many purposes: i)
Exposures at the SPS and at lower energy accelerator heavy ion beams for
calibration purposes and for fragmentation studies. ii) Searches for GUT and
Intermediate Mass Magnetic Monopoles (IMM), nuclearites, Q-balls and
strangelets in the cosmic radiation. The MACRO experiment in the Gran Sasso
underground lab, with ~1000 m^2 of CR39 detectors (plus scintillators and
streamer tubes), established an upper limit for superheavy GUT poles at the
level of 1.4x10^-16 cm^-2 s^-1 sr^-1 for 4x10^-5 <beta<1. The SLIM experiment
at the high altitude Chacaltaya lab (5230 m a.s.l.), using 427 m^2 of CR39
detectors exposed for 4.22 y, gave an upper limit for IMMs of ~1.3x10^-15 cm^-2
s^-1 sr^-1. The experiments yielded interesting upper limits also on the fluxes
of the other mentioned exotic particles. iii) Environmental studies, radiation
monitoring, neutron dosimetry.Comment: Talk given at "New Trends In High-Energy Physics" (experiment,
phenomenology, theory) Yalta, Crimea, Ukraine, September 27-October 4, 200
Search for Intermediate Mass Magnetic Monopoles and Nuclearites with the SLIM experiment
SLIM is a large area experiment (440 m2) installed at the Chacaltaya cosmic
ray laboratory since 2001, and about 100 m2 at Koksil, Himalaya, since 2003. It
is devoted to the search for intermediate mass magnetic monopoles (107-1013
GeV/c2) and nuclearites in the cosmic radiation using stacks of CR39 and
Makrofol nuclear track detectors. In four years of operation it will reach a
sensitivity to a flux of about 10-15 cm-2 s-1 sr-1. We present the results of
the calibration of CR39 and Makrofol and the analysis of a first sample of the
exposed detector.Comment: Presented at the 22nd ICNTS, Barcelona 200
Length measurement and stabilization of the diagonals of a square area laser gyroscope
Large frame ring laser gyroscopes are top sensitivity inertial sensors able to measure absolute angular rotation rate below prad s-1 in few seconds. The GINGER project is aiming at directly measuring the Lense-Thirring effect with an 1% precision on an Earth based experiment. GINGER is based on an array of large frame ring laser gyroscopes. The mechanical design of this apparatus requires a micrometric precision in the construction and the geometry must be stabilized in order to keep constant the scale factor of the instrument. The proposed control is based on square cavities, and relies on the length stabilization of the two diagonals, which must be equal at micrometric level. GP2 is the prototype devoted to the scale factor control test. As a first step, the lengths of the diagonals of the ring cavity have been measured through an interferometric technique with a statistical accuracy of some tens of nanometers, and they have been locked to the wavelength of a reference optical standard. Continuous operation has been obtained over more than 12 h, without loss of sensitivity. GP2 is located in a laboratory with standard temperature stabilization, with residual fluctuations of the order of 1 C. Besides the demonstration of the control effectiveness, the analysis of the Sagnac frequency demonstrates that relative small and low-cost ring lasers (around one meter of side) can also achieve a sensitivity of the order of nrad s-1 in the range 0.01-10 Hz in a standard environment, which is the target sensitivity in many different applications, such as rotational seismology and next generation gravitational waves detectors
Search for massive rare particles with the SLIM experiment
The search for magnetic monopoles in the cosmic radiation remains one of the
main aims of non-accelerator particle astrophysics. Experiments at high
altitude allow lower mass thresholds with respect to detectors at sea level or
underground. The SLIM experiment is a large array of nuclear track detectors at
the Chacaltaya High Altitude Laboratory (5290 m a.s.l.). The results from the
analysis of 171 m exposed for more than 3.5 y are here reported. The
completion of the analysis of the whole detector will allow to set the lowest
flux upper limit for Magnetic Monopoles in the mass range 10 - 10
GeV. The experiment is also sensitive to SQM nuggets and Q-balls, which are
possible Dark Matter candidates.Comment: Presented at the 29-th ICRC, Pune, India (2005
On the K^+D Interaction at Low Energies
The Kd reactions are considered in the impulse approximation with NN
final-state interactions (NN FSI) taken into account. The realistic parameters
for the KN phase shifts are used. The "quasi-elastic" energy region, in which
the elementary KN interaction is predominantly elastic, is considered. The
theoretical predictions are compared with the data on the K^+d->K^+pn,
K^+d->K^0pp, K^+d->K^+d and K^+d total cross sections. The NN FSI effect in the
reaction K^+d->K^+pn has been found to be large. The predictions for the Kd
cross sections are also given for slow kaons, produced from phi(1020) decays,
as the functions of the isoscalar KN scattering length a_0. These predictions
can be used to extract the value of a_0 from the data.Comment: 22 pages, 5 figure
Results of the Search for Strange Quark Matter and Q-balls with the SLIM Experiment
The SLIM experiment at the Chacaltaya high altitude laboratory was sensitive
to nuclearites and Q-balls, which could be present in the cosmic radiation as
possible Dark Matter components. It was sensitive also to strangelets, i.e.
small lumps of Strange Quark Matter predicted at such altitudes by various
phenomenological models. The analysis of 427 m^2 of Nuclear Track Detectors
exposed for 4.22 years showed no candidate event. New upper limits on the flux
of downgoing nuclearites and Q-balls at the 90% C.L. were established. The null
result also restricts models for strangelets propagation through the Earth
atmosphere.Comment: 14 pages, 11 EPS figure
Measurement of triple gauge boson couplings from WâșWâ» production at LEP energies up to 189 GeV
A measurement of triple gauge boson couplings is presented, based on W-pair data recorded by the OPAL detector at LEP during 1998 at a centre-of-mass energy of 189 GeV with an integrated luminosity of 183 pbâ»Âč. After combining with our previous measurements at centre-of-mass energies of 161â183 GeV we obtain Îș = 0.97_{-0.16}^{+0.20}, g_{1}^{z} = 0.991_{-0.057}^{+0.060} and λ = -0.110_{-0.055}^{+0.058}, where the errors include both statistical and systematic uncertainties and each coupling is determined by setting the other two couplings to their Standard Model values. These results are consistent with the Standard Model expectations
Heisenberg's Universal (lns)**2 Increase of Total Cross Sections
The (lns)**2 behaviour of total cross-sections, first obtained by Heisenberg
50 years ago, receives now increased interest both on phenomenological and
theoretical levels. In this paper we present a modification of the Heisenberg's
model in connection with the presence of glueballs and we show that it leads to
a realistic description of all existing hadron total cross-section data.Comment: 6 pages, 3 figure
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