A large acceptance scintillator detector with wavelength shifting fibre readout for search of -nucleus bound states

Abstract

A large acceptance scintillator detector with wavelength shifting optical fibre readout has been designed and built to detect the decay particles of Z-nucleus bound system (the so-called Z-mesic nuclei), namely, protons and pions. The detector, named as ENSTAR detector, consists of 122 pieces of plastic scintillator of various shapes and sizes, which are arranged in a cylindrical geometry to provide particle identification, energy loss and coarse position information for these particles. A solid angle coverage of $95% of total 4p is obtained in the present design of the detector. Monte Carlo phase space calculations performed to simulate the formation and decay of Z-mesic nuclei suggest that its decay particles, the protons and pions are emitted with an opening angle of 150 AE 20 , and with energies in the range of 25-300 and 225-450 MeV, respectively. The detailed GEANT simulations show that $80 % of the decay particles (protons and pions) can be detected within ENSTAR. Several test measurements using alpha source, cosmic-ray muons, etc. have been carried out to study the response of ENSTAR scintillator pieces. The in-beam tests of fully assembled detector with proton beam of momentum 870 MeV=c from the Cooler synchrotron COSY have been performed. The test results show that the scintillator fibre design chosen for the detector ARTICLE IN PRESS www.elsevier.com/locate/nima 0168-9002/$ -see front matter r .in (V. Jha).has performed satisfactorily well. The present article describes the detector design, simulation studies, construction details and test results. r

Experimental study of thep+6Li→η+7Bereaction 11.3 MeV above threshold

“…Then a second step occurs inside the nucleus η + n → π − + p with the two charged particles being emitted almost back to back. These two charged particles were recorded with a dedicated large acceptance detector [9].…”

ηbound state: theory and experiment

“…The high resolution magnetic spectrograph Big Karl [28] was used to identify 3 He Figure 3. The ENSTAR detector [27] surrounding the target. It consists of wedges from scintillating material.…”

“…The decay into a proton and π − with the two final particles emitted almost back to back to each other was measured with a dedicated detector ENSTAR [27]. It surrounds the target and one half of it is shown in figure 3.…”

The legacy of the experimental hadron physics programme at COSY

“…The ENSTAR detector [34] was designed to detect a pair of relatively low energy particles emerging from a target, with a fast particle being measured in the Big Karl spectrometer. A typical example, discussed in sect.…”

“…10.1, is where a 3 He is measured in Big Karl and a π − p pair, emitted from the target almost back to back, is registered in ENSTAR [35]. The basic design of this detector [34] is illustrated in Fig. 9.…”