31583612
Inclusion of fluctuations in Boltzmann-Uehling-Uhlenbeck dynamics: A method of simulation.
16744767
Absence of M2 Retardation in $^{35}Cl$: Evidence for Stronger Isospin-Mixing Effects in A=35 Mirror Nuclei
The lifetime of the 3163 keV, 7/2$^-$ isomeric state in $^{35}Cl$ that decays by a stretched M2 transition to the $3/2^+$ ground state, has been re-measured using the Doppler Shift Attenuation Method, by gating on the 1185 keV transition which directly feeds this state. This eliminates the uncertainties in the measurement arising from the direct feedings from the continuum. A mean life of 0.6$^{+0.5}_{-0.2}$ ps has been obtained from the present work. This is considerably smaller than the adopted value 45.3(6) ps. Implication of this major reduction in the lifetime has been pointed out.
38532982
Effect of trajectory fluctuations on nucleon drift and diffusion in deep inelastic heavy ion collisions.
The role of trajectory fluctuations on the first and second moments obtained in the mean trajectory approximation for the proton and neutron distributions of the projectile-like fragments produced in deep inelastic heavy ion collisions has been studied in the framework of stochastic transfer of single nucleons. At each instant of time the neutron and proton numbers of the colliding nuclei are considered to be given by dynamically evolving Gaussian distributions generating trajectory fluctuations. The first moments calculated in this method differ considerably from those obtained in the mean trajectory approximation for the systems with strong gradient in the driving force around the point of injection. The second moments, however, do not change appreciably for all the systems studied.
122669506
High voltage characteristic of large area cathode pad chambers for muon spectrometer of ALICE
AbstractLarge area Cathode Pad Chambers (CPC) with inner and outer radii of 23.7 cm and 117 cm respectively have been fabricated and tested for 2nd Tracking station of Muon Spectrometer of ALICE.The active area of this detector has a radiation length of less than 2 % and the frames are fabricated with Peek GF-30. The anode wire plane consists of 474 anode wires of which 53 % have lengths greater than 1 meter. The separation between the wire plane and the grounded cathode plane is 2.5 mm. The high voltage behaviour of the chamber have been tested under two situations.
With no support below the wires to reduce sagging of long wires.With a G10 strip-support whose dimension is 950 mm × 2 mm × 2.4 mm.
 The High Voltage (HV) tests show that a better stability is achieved when the strip support is implemented. Therefore this solution has been adopted for operation in ALICE.
53492385
Mechanical prototype of tracking chamber in station 2 in dimuon spectrometer of ALICE
To explore the physics of ultra-relativistic heavy-ion collision, a large ion collider experiment (ALICE) [1] is proposed to carry out at large hadron collider (LHC). Forward muon spectrometer (FMS) [2] is included in ALICE to look for the signals of quark gluon plasma (QGP) using dileptonic decay of heavy quarkonia (J=ψ , γ) produced in the collision as a probe. The production of these states will be suppressed in a deconfined medium of QGP which can be estimated from the invariant mass spectrum of dimuonic decay channel. The spectrometer is designed to track down the flight path of the dimuons with the help of five tracking stations from which the opening angle of the pair can be known by reconstruction and extrapolation of their tracks. The momenta of the pairs can be obtained from the deviation of the tracks in a dipole magnetic field. The invariant mass of the pair can be determined from the opening angle and momenta of dimuon pairs. Each of the five tracking stations is equipped with two planes of cathode pad chamber each divided into four quadrants to detect the position of the dimuon passing through them and reconstruct their tracks from their positions. The tracking chambers are designed following the basic feature of a position sensitive multi-wire proportional counter (MWPC) where an anode wire plane is interposed between two cathode planes and a high electric field is maintained near the anode with respect to the cathodes. The chambers are capable of providing X, Y position readout of an event from the charge distribution induced over the cathode planes equipped with pad matrices due to the avalanche produced in the gaseous medium. However, the mechanical design of the large chamber (diameter 2 m) for the second tracking station is a challenging task as it concerns good surface planarity to achieve position resolution better than 100 μm (necessary to meet mass resolution about 100 MeV) as well as minimum usage of material to keep radiation length low (2–3% of X0) in order to minimise the energy loss and scattering of the incident lepton. The calculation was carried out at IPN, Orsay to simulate a full scale quadrant with different design parameters and materials to study its mechanical characteristics [3,4]. In the simulation, various options in material and design aspects were studied to seek an optimum design for the chamber to enhance its mechanical
31869814
Heat partition in damped reactions.
The effect of driving force on the division of excitation energy between the asymmetric colliding partners in deep inelastic heavy-ion collisions is studied in the nucleon-exchange model. For this purpose an event-by-event analysis using Monte Carlo simulation technique is performed. It is seen that the fraction of the total excitation energy carried by the projectile-like fragment is sensitive to the mass drift. The model is also applied to analyze the correlation between fragment mass and excitation energy for a given total energy loss and significant correlation is found. The reactions induced by {sup 56}Fe at 9 MeV/nucleon and {sup 74}Ge at 8.5 MeV/nucleon on {sup 165}Ho are considered in our analysis and the calculated correlations are in good agreement with the results obtained from the kinematic coincidence experiments.
17525841
Probing supergravity grand unification in the Brookhaven g-2 experiment.
A quantitative analysis of ${\mathit{a}}_{\mathrm{\ensuremath{\mu}}}$\ensuremath{\equiv}1/2(g-2${)}_{\mathrm{\ensuremath{\mu}}}$ within the framework of supergravity grand unification and radiative breaking of the electroweak symmetry is given. It is found that ${\mathit{a}}_{\mathrm{\ensuremath{\mu}}}^{\mathrm{SUSY}}$ is dominated by the chiral interference term from the light chargino exchange, and that this term carries a signature which correlates strongly with the sign of \ensuremath{\mu}. Thus as a rule ${\mathit{a}}_{\mathrm{\ensuremath{\mu}}}^{\mathrm{SUSY}}$g0 for \ensuremath{\mu}g0 and ${\mathit{a}}_{\mathrm{\ensuremath{\mu}}}^{\mathrm{SUSY}}$0 for \ensuremath{\mu}0 with very few exceptions when tan\ensuremath{\beta}\ensuremath{\sim}1. At the quantitative level it is shown that if the E821 BNL experiment can reach the expected sensitivity of 4\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ and there is a reduction in the hadronic error by a factor of 4 or more, then the experiment will explore a majority of the parameter space in the ${\mathit{m}}_{0}$-${\mathit{m}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$ plane in the region ${\mathit{m}}_{0}$\ensuremath{\lesssim}400 GeV, ${\mathit{m}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$\ensuremath{\lesssim}700 GeV for tan\ensuremath{\beta}\ensuremath{\gtrsim}10 assuming the experiment will not discard the standard model result within its 2\ensuremath{\sigma} uncertainty limit. For smaller tan\ensuremath{\beta}, the SUSY reach of E821 will still be considerable. Further, if no effect within the 2\ensuremath{\sigma} limit of the standard model value is seen, then large tan\ensuremath{\beta} scenarios will be severely constrained within the current naturalness criterion, i.e., ${\mathit{m}}_{0}$,${\mathit{m}}_{\mathit{g}\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}$\ensuremath{\lesssim}1 TeV. \textcopyright{} 1996 The American Physical Society.