116926017
Observation of magnetic rotation in odd-odd Ag-104
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.
31583612
Inclusion of fluctuations in Boltzmann-Uehling-Uhlenbeck dynamics: A method of simulation.
123064298
Time of flight (TOF) spectrometer for accurate measurement of mass and angular distribution of fission fragments in heavy ion induced fission reactions
Abstract The performance of a dual time of flight (TOF) spectrometer using two 24 cm×10 cm area X – Y position sensitive Multi-Wire Proportional Counters (MWPC) is reported. Good separation of compound nuclear fission channel from elastic, quasi-elastic and non-compound fission channels have been achieved. Time calibration of the spectrometer using a technique, dependent on the detector independence of the mass or kinetic energy distributions gave a three times better mass resolutions compared to the conventional calibration technique using elastically scattered projectiles in a heavy ion induced fission reaction. Detail experimental methods in determining fission fragment mass and angular distribution have been presented and discussed.
121605686
Anomalous increase in width of fission fragment mass distribution inF19+Th232
Fission fragment mass distribution has been studied for the system $^{19}\mathrm{F}+^{232}\mathrm{Th}$ over an energy range of $105.4\phantom{\rule{0.3em}{0ex}}\text{MeV}$ to $84.2\phantom{\rule{0.3em}{0ex}}\text{MeV}$ in laboratory frame. For energies, above the Coulomb barrier, the variance of the mass distributions ${\ensuremath{\sigma}}_{m}^{2}$ varies linearly with temperature of the fused system, signifying statistical fusion-fission reaction. However, as energy decreases through the Coulomb barrier, a rapid increase in ${\ensuremath{\sigma}}_{m}^{2}$ is observed for the first time which may be a signal of onset of orientation dependent quasifission reaction.
21552932
Real Time Global Tests of the ALICE High Level Trigger Data Transport Framework
The High Level Trigger (HLT) system of the ALICE experiment is an online event filter and trigger system designed for input bandwidths of up to 25 GB/s at event rates of up to 1 kHz. The system is designed as a scalable PC cluster, implementing several hundred nodes. The transport of data in the system is handled by an object-oriented data flow framework operating on the basis of the publisher-subscriber principle, being designed fully pipelined with lowest processing overhead and communication latency in the cluster. In this paper, we report the latest measurements where this framework has been operated on five different sites over a global north-south link extending more than 10,000 km, processing a ldquoreal-timerdquo data flow.
119025520
Plasma lens experiments at the final focus test beam
We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam induced tunneling ionization of a working gas—the latter which has never been observed before. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders.
118014877
On stochastic cooling of bunched beams from fluctuation and kinetic theory
A theoretical formalism for stochastic phase-space cooling of bunched beams in storage rings is developed on the dual basis of classical fluctuation theory and kinetic theory of many-body systems in phase-space. The physics is that of a collection of three-dimensional oscillators coupled via retarded nonconservative interactions determined by an electronic feedback loop. At the heart of the formulation is the existence of several disparate time-scales characterizing the cooling process. Both theoretical approaches describe the cooling process in the form of a Fokker-Planck transport equation in phase-space valid up to second order in the strength and first order in the auto-correlation of the cooling signal. With neglect of the collective correlations induced by the feedback loop, identical expressions are obtained in both cases for the coherent damping and Schottky noise diffusion coefficients. These are expressed in terms of Fourier coefficients in a harmonic decomposition in angle of the generalized nonconservative cooling force written in canonical action-angle variables of the particles in six-dimensional phase-space. The formulation includes nonlinear pick-ups and kickers, multi-dimensional cooling with coupled degrees of freedom and instrinsic electronic noise of the feedback system. The effect of dynamic signal suppression arising from feedback loop induced collective correlations manifests naturally n a consistent solution of kinetic theoretic hierarchy for simple cases. For general situations, the existence of disparate time-scales allows one to use simple fluctuation theoretic results but with transport coefficients dynamically suppressed by factors determined independently from the well-known Vlasov theory. The general coupled-mode matrix for the longitudinal and transverse signal suppression for bunched beams is derived and solved in the limit of no synchrotron band overlap. The distinctive feature of synchrotron band overlap in the bunched beam Schottky signal for a higher bandwidth-system is discussed. The signal suppression matrix describing the tensorial collective response of a coasting beam with coupled transverse cooling is also derived. Comparison of analytic results to a numerical simulation study with 90 pseudo-particles in a model cooling system is presented. Estimates of transverse cooling rates for bunches in a prototype high-energy storage ring with typical large bandwidth feedback systems are provided.
119684047
ZAP User's Manual
The use and content of Phase I of the accelerator physics code ZAP, which calculates the performance of a storage ring in terms of the effects of beam intensity dependent phenomena and the limitations they impose. A brief overview is provided of the code and the types of calculations that can be performed with it. The types of calculations available include: single bunch thresholds, single bunch longitudinal parameters and energy scaling tables, longitudinal coupled-bunch instabilities, transverse coupled-bunch instabilities, gas scattering lifetime, free electron laser formulae, intrabeam scattering, Touschek scattering, and ion trapping formulae. Examples of the required inputs and resultant outputs for each of the options are given. The theoretical foundations behind ZAP are summarized, providing the relevant formulations, physical models, and particularly the equations used in the code in evaluating the various effects that are computed. (LEW)
102345903
Advances in beam physics and technology: Colliders of the future
Beams may be viewed as directed and focussed flow of energy and information, carried by particles and electromagnetic radiation fields (i.e. photons). Often, they are brought into interaction with each other (e.g. in high energy colliders) or with other forms of matter (e.g. in fixed target physics, synchrotron radiation sciences, neutron scattering experiments, laser chemistry and physics, medical therapy, etc.). The whole art and science of beams revolve around the fundamental quest for, and ultimate implementation of, mechanisms of production, storage, control and observation of beams—always directed towards studies of the basic structures and processes of the natural world and various practical applications. Tremendous progress has been made in all aspects of beam physics and technology in the last decades—nonlinear dynamics, superconducting magnets and radio frequency cavities, beam instrumentation and control, novel concepts and collider paradigms, to name a few. We will illustrate this progress via...
11934750
Measurements of radiation near an atomic spectral line from the interaction of a 30 GeV electron beam and a long plasma.
Emissions produced or initiated by a 30-GeV electron beam propagating through a approximately 1-m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creation of plasma, and estimates of neutral and plasma density have been extracted. Increases in visible background radiation, consistent with increased plasma recombination emissions due to dissipation of wakefields, were simultaneously measured.