M. Kurosawa

Fine Pitch and Low Material Readout Bus for the Silicon Pixel Detector in the PHENIX Vertex Tracker

The silicon pixel detector will be installed in summer 2009 as part of the RHIC-PHENIX silicon vertex tracker (VTX) upgrade at the Brookhaven National Laboratory. The VTX consists of a silicon pixel detector and stripixel detector. For the construction of the silicon pixel detector, we have developed a fine pitch and low material readout bus as the backbone parts of the VTX. In this article, we report the development of the readout bus.

Scintillating Track Image Camera-SCITIC

A new type of track detector, scintillating track image camera (SCITIC) has been developed. Scintillating track images of particles in a scintillator are focused by an optical lens system on a photocathode on image intesifier tube (IIT). The image signals are amplified by an IIT-cascade and stored by a CCD camera. The performance of the detector has been tested with cosmic-ray muons and with pion- and proton-beams from the KEK 12-GeV proton synchrotron. Data of the test experiments have shown promising features of SCITIC as a triggerable track detector with a variety of possibilities.

Hyperon Scattering Experiments with a New Tracking Detector “SCITIC”

A new tracking detector, scintillating track image camera (SCITIC) was used for hyperon-scattering experiments. Since the hyperon lifetimes are short, the low-energy hyperon-nucleon scattering can be studied only with a track detector used as an active target. The present experiment has shown that the SCITIC is a promising detector for the hyperon scattering experiments. Polarized hyperons Σ+ were produced through p(π+, K+)Σ+ reactions with a 1.6 GeV/c pion beam on a liquid scintillator of the active target. Three sets of SCITIC were used to record the pictures of Σ+ production and scattering. A kaon spectrometer was used to trigger the SCITIC with a signal of kaon from the reaction. Left/right asymmetries of the Σ+p scattering were determined through analyses of the pictorial data, and the results were in accordance with a quark-model prediction that the asymmetry was large in the Σ+p scattering while it was small in the ΛN case.

Search for the H-dibaryon resonance in {sup 12}C (K{sup -},K{sup +}{lambda}{lambda}X)

The H-dibaryon resonance was sought by a {lambda}{lambda} invariant mass spectrum that was obtained by the {sup 12}C (K{sup -},K{sup +}{lambda}{lambda}X) reactions. We observed a bump near the {lambda}{lambda} threshold, as reported by the previous experiment (KEK E224), with better statistics. Data were compared with results of a cascade model calculation including {lambda}{lambda} final state interactions consistent with the newly measured binding energy of {sub {lambda}}{sub {lambda}}{sup 6}He. No significant enhancements above levels of the model predictions were observed. The resulting upper limit for the production cross section of the H with a mass range between the {lambda}{lambda} and {xi}N threshold is found to be 2.1 {+-} 0.6 (stat.) {+-} 0.1 (syst.) {mu}b/sr at a 90% confidence level.

H-dibaryon search by KEK-E522

We searched for the H-dibaryon resonance in the ΛΛ invariant mass spectrum obtained by 12C(K −, K + ΛΛX) reactions using a scintillating fiber active target. We observed enhanced ΛΛ production near the threshold, as found in a previous KEK experiment, with improved statistics. Data were compared with the results of a cascade model calculation including ΛΛ final state interactions consistent with the recently measured binding energy of the double-Λ hypernucleus. No significant enhancements above the levels predicted by the model were observed. The upper limit for the production cross section of the H-dibaryon with a mass range between the ΛΛ and ΞN threshold is found to be 2.1 μb/sr at a 90% confidence level.

Image analysis of SCITIC for hyperon scattering experiments

A new scintillation-track-image detector, SCITIC, has been developed and successfully used as an active target for hyperon-scattering experiments. The principle and practical use in experiments of SCITIC have bean reported. In this paper, we present the results of a reanalysis of SCITIC data by a new method. The new method assures more precise three-dimensional (3D) track reconstruction than before by introducing a way of critically checking and an iterating data processing. After a brief presentation of the experimental setup and procedure of data taking, details of the image analysis are discussed. With the new analysis, the precision of the data for the Σ+p scattering experiment was improved leading to the conclusion that the Σ+p spin–orbit interaction is comparable to the NN interaction, and that the angular dependence of analyzing power is in good agreement with a theoretical prediction.