Hyperon Scattering Experiments with a New Tracking Detector “SCITIC”

Abstract

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 AE þ were produced through pð þ ; K þ ÞAE þ 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 AE þ 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 AE þ 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 AE þ p scattering while it was small in the ÃN case.

Image Analysis of SCITIC for Hyperon Scattering Experiments

“…The major objective was to determine the spin-orbit (LS) interaction between a AE þ -hyperon and a proton for comparison with that of Ã-hyperons, where the interaction was shown to be small. [3][4][5] The present series of experiments, 2,6) however, have shown that the AE þ N spin-orbit interaction is large in contrast to that in the case of ÃN, 7) consistent with theoretical predictions by Povh and Pirner, 8,9) and Yazaki. 10) Although the above conclusion has provided an important base for understanding hyperon-nucleon interactions, data analysis was premature and the conclusion was qualitative.…”

“…6) Based on our experience in E452A, the experimental setup and data-taking system were redesigned and rebuilt for the major experiments E452B and C, as described in our previous paper. 2) In the present paper, we describe a reanalysis of the data from E452B and C, including the data used in the previous paper. 2)…”

“…2) In the present paper, we describe a reanalysis of the data from E452B and C, including the data used in the previous paper. 2)…”

“…In the past several years, we have developed a new trackimage detector, SCITIC, for studies spin-dependent hyperon-nucleon interactions at KEK. The principle and performance of SCITIC were reported at an earlier stage 1) and its application to hyperon-scattering experiments was discussed in a previous paper 2) together with the presentation of experimental results.…”

“…The new analysis method was developed to use the redundancy of having three SCITIC images to obtain a 3Dtrack pattern for critical judgments. The track reconstruction was repeated until the result satisfied a criterion based on 2 .…”