Characterization results are given for an original ASIC allowing continuous acquisition of ionising radiation images in spectroscopic mode. Ionising radiation imaging in general and spectroscopic imaging in particular must primarily be guided by the attempt to decrease statistical noise, which requires detection systems designed to allow very high counting rates. Any source of dead time must therefore be avoided. Thus, the use of on-line corrections of the inevitable dispersion of characteristics between the large number of electronic channels of the detection system, shall be precluded. Without claiming to achieve ultimate noise levels, the work described is focused on how to prevent good individual acquisition channel noise performance from being totally destroyed by the dispersion between channels without introducing dead times. With this goal, we developed an automatic charge amplifier output voltage offset compensation system which operates regardless of the cause of the offset (detector or electronic). The main performances of the system are the following: the input equivalent noise charge is 190e rms (input non connected, peaking time 500ns), the highest gain is 255mV/fC, the peaking time is adjustable between 200ns and 2μs and the power consumption is 10mW per channel. The agreement between experimental data and theoretical simulation results is excellent.

To investigate the effects of neutrons on MSGCs, the gain of several detectors was measured before and after irradiation with a flux of 106neutrons/cm2s in the CEA (Saclay) ISIS reactor facility. On one of these prototypes the induced activity was measured after the irradiation.

A set of CMS MicroStrip Gas Chambers (MSGC) was exposed to a high-intensity 3GeV/c pion beam at a CERN PS facility for a period of two weeks. The performance of the detectors is reported in terms of stability of efficiency and response to minimum ionising particles as well as to more heavily ionising fragments generated by nuclear interactions.

New data from the CERN WA97 experiment on Xi and Omega production in p-Pb and Ph-Ph collisions at 158 GeV/c per nucleon are presented. They confirm the recent indication(1) that the Omega/Xi ratio is significantly higher in Ph-Ph compared to p-Ph reactions.

Preliminary results from WA97 measurements on Λ, Ξ and Ω production in lead-lead and proton-lead collisions are presented, along with a comparison of WA97 proton-lead data with previous WA85 proton-tungsten results. The ratio ΩgX seems to be enhanced in lead initiated reactions compared to proton initiated reactions.

Preliminary results from WA97 measurements on Λ, Ξ and Ω production in lead-lead and proton-lead collisions are presented, along with a comparison of WA97 proton-lead data with previous WA85 proton-tungsten results. The ratio Ω/Ξ seems to be enhanced in lead initiated reactions compared to proton initiated reactions.

The need to understand surface and space charging of microstrip gas chambers requires a study of transverse diffusion for inhomogeneous electric fields. A differential equation is deduced for the time dependence of the root-mean-square dispersion of the distribution of drifting charges. Its solution yields estimates of electron clouds approaching the anodes, and of ion clouds leaving them. Comparisons to measurements are presented.

WA97 is designed to study strange and multi-strange baryon and anti-baryon production in 160 A GeVc PbPb collisions at the SPS with a telescope of silicon microdetectors. Four planes of silicon pixel detectors were successfully employed during the 1994 Pb run. A total of 60M central PbPb events were collected. We describe the experimental setup and report on some preliminary results from the off-line analysis.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Douglas E. Greiner, E. Andersen, R. Blaes, M. Cherney, B. de la Cruz, C. Fernández, C. Garabatos, J. A. Garzón, W. M. Geist, D. E. Greiner, C. Gruhn, M. Hafidouni, J. Hrubec, P. G. Jones, E. G. Judd, J. P. M. Kuipers, M. Ladrem, P. Ladrón de Guevara, G. Lo/vho/iden, J. MacNaughton, J. Mosquera, Z. Nathaniec, J. M. Nelson, G. Neuhofer, C. Pérez de los Heros, M. Pló, P. Porth, B. Powell, A. Ramil, H. Rohringer, I. Sakrejda, T. F. Thorsteinsen, J. Traxler, C. Voltolini, K. Wozniak, A. Yañez, R. Zybert, NA36 Collaboration; Strangeness production as a function of centrality. AIP Conf. Proc. 20 July 1995; 340 (1): 207–222. https://doi.org/10.1063/1.48722 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

Measurements of the production of Λ particles in S+Pb and S+S collisions at a beam momentum of 200 GeV/c per nucleon are presented. The S+Pb data was taken with two different experimental configurations, and the results agree well with each other. The effects of a new Monte Carlo simulation of the NA36 TPC on the efficiency calculations are discussed. The Λ rapidity and multiplicity distributions are then compared to three theoretical models of heavy ion interactions, and to the NA35 results. There is still a significant disagreement between the two experiments. The comparison to the models indicates that reinteractions of secondaries are important in explaining the observed Λ yields. Finally, the yields of doubly strange baryons in S+Pb interactions have been recalculated using the new efficiencies. The ratios of double to singly strange baryons are unchanged from the previously published results.

Gas gain variations as functions of time have been observed with microstrip gas chambers. They are attributed here to charging of the substrate surface between electrodes. Based upon the concept of quasi-electrostatic fields a rule of charge accumulation is derived. Gas conductance is studied in order to apply the rule to a surface exposed to gas. A relation between substrate resistivity and the rate of detected particles for stable gain operation is then obtained by means of this rule. A comparison with experimental results yields good agreement.

SPb and SS interactions at 200 A GeV/c, as measured by the NA36 experiment at CERN, have been classified according to the number of participant protons of the projectile, by means of a precise identification of the charge of the projectile fragment produced. Rapidity and transverse momentum spectra of π− associated with the production of Z = 10 to Z = 15 projectile fragments are presented and compared to three models with different mechanisms of final particle production.

Experiment NA36 at the CERN North Area was designed to measure, with high statistics, strange particles in Sulfur Lead interactions at 200 GeV/c per nucleon in a wide range of acceptance and to give possible hints to the existence of the Quark Gluon Plasma (QGP). It uses a TPC (1.0 × 0.5 × 0.5 m 3) in a 2.7 Tesla field situated approximately 1.5cm above the beam to avoid beam fragments disturbing the chamber. Silicon beam counters, a Čerenkov counter and a forward calorimeter select good beams, trigger on sulfur interactions and determine the centrality of the reactions. The beam hits a lead target of 5% interaction length 60 cm away from the chamber entrance. We use about 1 million events of S+Pb interactions and a smaller sample of p+Pb events for comparison.

The yields of LAMBDA, LAMBDABAR, and XI-, XI+BAR have been measured close to mid-rapidity in sulphur reactions on a Pb target at 200 GeV/c per nucleon beam momentum. Fully corrected production ratios of LAMBDABAR/LAMBDA, XI+BAR/XI, XI-/LAMBDA and XI+BAR/LAMBDABAR are presented. The ratios have been analysed both in the context of a rapidly disintegrating quark-gluon plasma and a hadronic resonance gas. Our analysis shows that the hadron gas model is sufficient to explain the observed particle yields.

The production of the strange particles Λ, \̄gL and K0S in p+Pb collisions at 200 GeVc has been measured using the NA36 TPC. Rapidity distributions and multiplicity dependences are presented and compared to model calculations. Reinteractions in the target are important to describe the observed spectra. Inverse slopes T |t200 MeV are extracted from the transverse mass distributions.

Measurements of the production of singly and doubly strange particles in S + Pb collisions at a beam momentum of 200 GeV/c per nucleon are presented. The yield of singly strange particles as a function of negative particle multiplicity has been measured. Rapidity and transverse momentum distributions from events consistent with a maximum impact parameter of 9 fm are compared with the predictions of Fritiof 7.02, Venus 4.10 and RQMD 1.08. The comparison illustrates the importance of re-interactions of secondaries and suggests that additional physical processes are required to be incorporated into the event generators. The analysis of strange particle ratios indicates that strangeness phase space is not saturated in these collisions.