Yu. Galaktionov

An antimatter spectrometer in space

Abstract We discuss a simple magnetic spectrometer to be installed on a satellite or space station. The purpose of this spectrometer is to search for primordial antimatter to the level of antimatter/matter ≈10 −9 , improving the existing limits obtained with balloon flights by a factor of 10 4 to 10 5 . The design of the spectrometer is based on an iron-free, NdFeB permanent magnet, scintillation counters, drift tubes, and silicon or time projection chambers. Different design options are discussed. Typically, the spectrometer has a weight of about 2 tons and an acceptance of about 1.0 m 2 sr. The availability of the new NdFeB material makes it possible for the first time to put a magnet into space economically and reliably.

Hadron calorimetry in the L3 detector

Abstract The characteristics of the L3 hadron calorimeter as realized in the observation of hadronic jets and other events from e + e − collisions at LEP are presented and discussed. The pattern-recognition algorithm utilizing the fine granulatiry of the calorimeter is described, and the observed overall resolution of 10.2% for hadron jets from Z decay is reported. The use of the calorimeter in providing information on muon energy losses is also noted.

Measurement of neutron-proton charge exchange scattering at 8, 19 and 24 GeV/c

Abstract The t -dependence of the differential cross-section for elastic neutron-proton charge exchange scattering has been measured at 8, 19.2 and 24 GeV/ c . The extremely narrow peak in the forward direction, previously observed for momenta up to 8 GeV/ c , presists at the higher momenta, and the t -dependence shows practically no change with energy. Approximate values of the absolute cross-section were also determined for these momenta.

The parallel plate chamber as a detector for fast, radiation resistive calorimetry

We have built and tested a thin (1 mm) single gap parallel plate chamber (PPC) with planar electrodes, working in the avalanche mode. It consists of sixteen 1 mm gap cells, each 126.5×126.5 mm2. The gas filling is pure isobutane at NTP. The chamber operates without breakdown up to the electric field of 60 kV/cm. The PPC has a very fast response, and a time resolution of a few nanoseconds. The detection efficiency is close to unity. No saturation effects were observed for collected charges up to 1 pC. Results of the scanning of the electron and hadron shower development, using the prototype detector plane, are presented.

The performance of a uranium gas sampling calorimeter

Abstract The performance of a uranium gas sampling hadron calorimeter is described. It has been observed that the hydrogen content of the gas mixture plays an important role in defining the behaviour of this type of calorimeter. The low-energy neutrons emerging from a hadron cascade are detected much more efficiently in a hydrogenous gas; thus leakage or containment of these neutrons becomes an important feature of the calorimeter setup.

Elastic backward scattering of negative pions on neutrons at 23 and 40 GeV/c

Abstract The backward elastic scattering reaction π − p → p π − at momenta 25 and 38 GeV/ c have been measured using a magnetic spectrometer with hybrid chambers. The experimental data on the dependence of the cross section d σ /d u on the momentum transfer u as well as the energy dependence d σ /d u at u = 0 are given.

Neutron-nucleus total cross-sections between 8 GeV/c and 21 GeV/c 1

Abstract Total cross-sections for neutrons on Be, C, Al, Cu and Pb have been measured to an accuracy of about 1% at average neutron momenta of 8, 11, 14 and 21 GeV/ c . For all elements they drop smoothly 1 by about 3% between 8 and 21 GeV/ c , and have a momentum dependence similar to the pp and np total 1 cross-sections. Indeed if the cross-sections are normalized to the np total cross-section, no momentum dependence can be observed. The data are compared with calculations based on the Glauber model.

Measurement ofπ0production at large transverse momentum inπ−p,π+p, andppcollisions at 300 GeV/c

Cross sections for inclusive ..pi../sup 0/ production at large transverse momentum p/sub T/ were measured in ..pi../sup -/p, ..pi../sup +/p, and pp collisions at 300 GeV/c. The cross-section ratio sigma(..pi../sup -/p..--> pi../sup 0/X)/sigma(..pi../sup +/p..--> pi../sup 0/X) was found to be consistent with unity in the p/sub T/ region of 1 to 5 GeV/c. The cross-section ratio sigma(..pi../sup +/p..--> pi../sup 0/X)/sigma(pp..--> pi../sup 0/X) however is growing with increasing p/sub T/ and increasing ..pi../sup 0/ c.m.-system rapidity in agreement with parton-model expectations, where the partons in the pions have on average higher momenta than in the proton.

Measurement of np elastic scattering at high energies and very small momentum transfers

Abstract The np elastic differential cross section has been measured for incident neutron momenta 100–400 GeV/ c in the | t | range 6 · 10 −6 − 5 · 10 −1 (GeV/ c ) 2 . The np data of this experiment provide a first direct measurement of the hadronic amplitude for | t | −2 (GeV/ c ) 2 , which is consistent with the extrapolations from higher | t | values. Our data for | t | −4 (GeV/ c ) 2 are consistent with a rise which can be attributed to Schwinger scattering, caused by the interaction of the neutron magnetic moment with the proton.

Neutron-proton total cross-sections between 8 GeVc and 21 GeVc☆

Abstract Neutron-proton total cross-sections were measured in the momentum range from 8 GeV/ c to 21 GeV/ c with an accuracy of better than 2% using a 0 o neutron beam at the CERN Proton Synchrotron. The np total cross-section drops from 39.7 mb at 8 GeV/ c at 21 GeV/ c , and thus follows closely the pp total cross-sections in this momentum interval.