J.A. Buchanan

Rapidity distributions of Ks0's and Λ's produced by 14.6×A GeV/cSi beams on Si and Pb targets

Abstract We present the first measurement at AGS energies of rapidity distributions of K s 0 and Λ production with silicon beams on silicon and lead targets. The measurements cover the rapidity region of 2.0 y K s 0 s and 1.4 y Λ s.

Time-resolved extended X-ray absorption fine structure

Abstract We have constructed a time-resolved extended X-ray absorption fine structure spectrometer for measuring transient structures of dynamic systems. Its time resolution can be varied from nanoseconds to 1000 μs.

CAMAC Multi-Microprogrammed IO Processor

A CAMAC Branch Driver is described which provides multiple channel direct memory access to a host computer via a single DMA interface. Command lists in computer memory select micro-programmed sequences, stored in a fast-access Control Memory, which transfer data between CAMAC devices and lists in computer memory.

H0 candidates from the decay H0 → Σ−p, observed in heavy ion collisions with 14.6 × A GeV/c Si beam on Pb target

Abstract We present H 0 candidate events, where the H 0 is observed through the decay H 0 → Σ − p . These decays are reconstructed in the three TPC modules of E810 while triggering on central Si Pb events at 14.6 × A GeV/c Si beam.

Rapidity distributions and nuclear transparency in heavy ion collisions

Abstract We have measured the rapidity distributions for charged particles produced in SiAu collisions at 14.6× A GeV/ c . No evidence is seen for enhanced production of protons at high rapidity as recently postulated based on fits to earlier data.

Transverse momentum distributions of π− from 14.6A GeV/c silicon ion interactions in copper and gold

Abstract A measurement of the transverse momentum spectrum of negatively charged tracks from AGS energy silicon ion collisions is presented. The spectrum has a different shape than that of nucleon-nucleon collisions at approximately the same energy. The transverse mass spectrum is well represented by a sum of two exponentials with different slopes and may be reasonably well accounted for by a model of pion production in interacting nuclear matter that includes resonance production and decay.

A TPC for large solid angle relativistic ion experiments

A TPC (time projection chamber) detector system has been developed to function in the very-high-multiplicity environment of relativistic-heavy-ion experiments. A TPC was chosen because it directly gives three-dimensional points on the tracks, which is a very significant help for track-finding. Of prime importance is a combination of high efficiency, low noise, and two track resolution capability. A significant development is a system of hybridized, high-sensitivity, on-chamber digitizing electronics. A description of the TPC modules, the digitizing electronics, and test results is given. >

Ξ− production in heavy ion collisions at the AGS☆

Abstract We report the first observation of Ξ − in heavy ion collisions at the AGS. The lifetime of Ξ − measured agrees very well with the particle data group value. We present the observed Ξ − effective mass spectrum and the rapidity distribution after acceptance correction. In the measured rapidity region (1.4−2.9) for 14.6 GeV/ c Si on Pb, we obtained a yield of 0.25 ± 0.04 Ξ − per central event and a ratio of N ( Ξ − )/ N ( Λ ) = 0.12 ± 0.02 using a fireball + model (a model which includes a fireball plus a term simulating a cascade) for acceptance correction (see text for systematic error). This result is larger than any cascade model prediction so far.

Recent results from E-810

Abstract I discuss data from E-810 including K 0 and Λ production, the rise in production of negative particles at small m ⊥ , and the rapidity distributions. The data are compared to various models; in particular they do not agree with a model indicating large nuclear transparency.

Effects of high beam rates on TPCs

The TPCs (Time Projection Chamber) used in E-810 at the AGS (Alternating Gradient Synchroton) were exposed to silicon ion fluxes equivalent to more than 10{sup 7} minimum ionizing particles per second to measure the distortion of the electric field caused by positive ions in the drift region. Results of these tests are presented and the consequences for the TPC based experiment at RHIC (Relativistic Heavy Ion Collider) are discussed.