[en] The modification and the practical use of a magnetic calorimeter detector (MAC) for the TRISTAN experiment are discussed. As for the central drift chamber, the radius of 50 cm is kept, the identification of ''wrong sign'' μ⁺μ^- or e⁺e^- is scarcely required, and the solenoidal field is increased to the design limit, 10 kG. The spatial resolution will be about 100 μm, and a factor of 5 or 10 in the spatial resolution will be obtained by using additional field wires. The entire central drift chamber can be replaced by a TPC which has the additional advantage of dE/dx and particle identification capabilities. For the electromagnetic calorimeter, about 10⁴ crystals of bismuth germanate (Bi₄Ge3012 = BGO), of which the energy resolution was proven to attain a few MeV, are used. A preamplifier, a shaping amplifier and a logarithmic amplifier are attached to each crystal. The BGO shell is about 30 cm thick. The new solenoid coil made of copper or aluminum has an 80 cm inside radius. The hadron calorimeter is used with minor repair and some electronics upgrade. As for the muon drift system, the momentum resolution is estimated to be 0.3 at 30 GeV. A number of physics objectives for e⁺e^- annihilation at TRISTAN energy with the practical use of the proposed detector are summarized: i) the calorimetry experiments including R measurement near the Z⁰ pole, jet studies, μ^+- charge asymmetry, e^+- charge asymmetry, μ^+- and e^+- inclusive spectra, and quark flavor tagging, ii) the precise γ or e^+- energy measurement including e⁺e^- → γ anti-ν near the Z⁰ pole, γ (t anti-t) + H, and toponium studies, iii) the lifetime measurement of a 15 GeV tau, and the hadron identification and inclusive spectra. (Ito, K.)

[en] What performance can be expected for dedicated detectors was the main theme of discussion in this subgroup. In the case of dedicated detectors, it is possible to consider the requirement for a specific physics issue and neglect others. Therefore, single purpose detectors can be designed so that they have an ability to take clear data with good resolution, good S/N ratio and considerably low systematic error. In the TRISTAN energy range, the event rate of interesting process is estimated to be low, and the background level may be high. In order to obtain the significant signals of a rare process, excellent dedicated detectors are required. A brief survey of typical detectors was carried out. For example, toponium and Higgs physics require the good resolution of gamma detection. In the case of low energy gamma measurement, bismuth germanate seems to be a best shower material for electromagnetic calorimeters. Lead glass is often used for high energy gamma measurement because of the good energy resolution, and scintillation glass may be a detector for medium energy gamma. For accurate decay vertex measurement, solid state detector hodoscopes will be available. Compact BGO balls, huge water balls, magnetized iron boxes and modified MAC detectors are proposed for their special purposes. (Kako, I.)

[en] The design of the large cylindrical drift-chamber of the TASSO-detector at PETRA is described. A summary of the experience gained in the three years of operation is given. An outstanding feature is the high reliability of the driftchamber system. So far a spatial resolution of omicron = 200 μm has been achieved. The momentum resolution was measured with cosmic ray tracks, μ-pairs and Bhabha-events, consistently yielding a value of dpsub(t)/psub(t) = 1.4 % psub(t) (psub(t) in GeV/c). The errors in the track parameters are in good areement with the predictions of a MC-simulation. Finally, suggestions for future improvements are made. (author)

[en] Some processes in the electron-positron interaction in the TRISTAN energy range were studied using the QCD Monte Carlo program written by Ali et al. The processes which were studied are; electron + positron → one photon → QQ(bar), QQ(bar)g, QQ(bar)gg, where Q = u, d, s, c, b Fquarks and g is a gluon; electron + positron → one photon → tt(bar) → X, where X = three gluons, weak decay products, Higgs + one photon, and two gluons + one photon; electron + positron → one photon → heavy lepton pair; two photon processes. The general properties of final states in QCD jets are displayed, which include single particle spectra, multiplicity, sphericity, spherocity, and thrust distribution. Based on the analysis, several remarks are made. It is very hard to find the D peak in the invariant mass sperctra for the momentum resolution of 0.3 % of the momenta. One-photon processes can be well separated from two-photon processes. Electron can be identified with a shower counter. The measurement of the leading kaon momentum spectra may be better for the study of t-quark decay mode. Energy resolution should be better than 10 % of √E if it is necessary to see the photon peak corresponding to the Higgs + photon process in the inclusive photon spectrum. Hadron calorimeter makes the one photon peak in a visible energy spectrum narrower, and improves the one- and two-photon process separation. (Ito, K.)

[en] We propose a 4π magnetic spectrometer as a universal detector at TRISTAN E⁺E^- collider. A part of the simulated performance is reported here; the detection of hadronic one-photon-annihilation events and the search of the fundamental scalar particle. (author)

[en] A universal detector for the 60 GeV e⁺e^- colliding beam TRISTAN was proposed. The electron identification, which is important in QED, flavor physics, heavy leptons and deep inelastic esup(r) scattering for photon structure functions, should be carried out by a combination of two or three independent ways: a combination of a dE/dx drift chamber and an array of Pb-glass shower counters, and a dE/dx drift chamber plus a liquid argon counter system. A high pressure drift chamber, such as a new Mark 2 vertex detector, is sufficient to do the above-mentioned physics. For the dE/dx drift chamber, a jet chamber is considered. If more than 3 standard deviations are required in e/π separation at the momentum of 3 GeV/c, the radius of the jet chamber will be 2 meters. Although the large diameter results in a large magnet coil, a large shower counter, more TOF counters and so on, these disadvantages will be compensated by the better TOF resolution and the smaller probability of particle overlap in shower counters. Considering many difficult hardware and operational problems, the difference in e/π separability does not appear between 1 and 10 atom of the gas pressure in the chamber, accordingly, atmospheric pressure was chosen as the gas pressure for the simplicity of the mechanical construction. Finally, the momentum resolution of the drift chamber was calculated with 200 cm in outer radius and 5 kG magnetic field, and it was found to be more than enough. All parameters for this design are listed. (Ito, K.)

[en] Performance of BGO-bar crystal is briefly described including the optical properties, the energy resolution and the uniformity. BGO-bar is highly resistive to radiation damage, proving that it is ideal to be used in high energy E⁺E^- storage ring detectors. After briefly discussing the BGO-bar detectors for LEP and CESR II, a ''BGO-bar Ball'' is proposed for a compact detector primarily dedicated to Higgs search at TRISTAN. If a hadron calorimeter is added outside the ''BGO-bar Ball'', the other important physics including accurate measurement of R and top quark searches through jet analyses will be possible. (author)

No abstract available

[en] First, the PLUTO detector, which has recently been improved for the γγ detection, is presented. The central magnetic field is 16.5 kG, and the momentum is measured with sigma (p)/p = 8 % . p(GeV/c). The central detector region has a good shower counter coverage down to theta = 15 deg. Tracking and muon coverage are down to theta = about 30 deg. The forward spectrometer has the theta angle coverage of 4.9 - 14.9 deg, and it can analyze 40 -- 50 % of particles from γγ - multihadrons. It can also identify electrons, hadrons below 1 - 2 GeV/c and muons having momentum over about 1 GeV/c. The shower counter placed before the quadrupoles, which are at distance of 4.4 m form the interaction point, detects electrons with theta = 1.6 - 4.3 deg. This PLUTO detector will be further improved to complete its transformation into a modern state-of-the-art detector, and will be installed in PLUTO after the 1982 run in preparation for the next PETRA run. Second, a new γγ detector is proposed, based on the following criteria: good solid angle coverage, compactness and optimization for the detection of single photon annihilation events. The angular coverage of this detector is theta = 6 - 90 deg. A central detector of jet chamber type has a 15 kG magnetic field, and enables a momentum precision of sigma (p)/p = 3% . p(GeV/c) and a dE/dx precision of about 18 % (FWHM). This detector would carry out electron identification with a liquid argon counter and dE/dx measurement. The practicality of this new detector remains to be demonstrated. (Ito, K.)

[en] The general plan of constructing the TRISTAN e⁺e^- colliding beam experimental halls may be divided into two parts. The first step is to construct two test-experimental halls associated with the 6.5 GeV x 6.5 GeV e⁺e^- accumulator ring, and the second step is to build four experimental halls at the 30 GeV x 30 GeV e⁺e^- TRISTAN main ring. At this workshop, extensive discussions on the detailed design of the four main ring experimental halls have been made. Four experimental areas will be built at the main ring, and two test-experimental halls at the accumulating ring. Among the four areas at the main ring, two will be used for electron-proton possible as well as electron-positron colliding beam experiment. The other two will be used exclusively for e⁺e^- colliding experiments. Only a preliminary design has been made for these four experimental areas. A tentative plan of a larger experimental hall includes a counting and data processing room, a utility room, and a radiation safety control room. Two smaller halls have simpler structure. The figures of the experimental halls are presented. The two test-experimental halls at the accumulator ring will be used to test the detectors for e⁺e^- colliding experiments before the final installation. The utility rooms designed for the halls are used to supply coolant and electric power of superconducting magnets. At the workshop, various ideas concerning the preliminary plan are presented. (Kato, T.)