A.S. Ito

A search for new massive particles

Abstract We have searched for an almost stable, charged particle produced in 400 GeV proton-nucleus collisions. A total of 5 × 10 10 light secondary particles were sampled in a secondary beam of 70 GeV/ c momentum. If a 4.5 to 6.0 GeV mass particle is produced with a cross section comparable with the production cross section of the upsilon then this experiment places an upper limit on the lifetime of such a particle of about 5 × 10 −8 s.

Longitudinal Shower Development in a Lead-Scintillator Calorimeter as a Tool to Separate Pions an Electrons at 10-50 Gev Energies

Introduction Since multi-hundred GeV particle accelerators have been built for high energy physics research, calorimetry has become a very important method not only for measuring particle energy but also for identifying particle species. Consequently, there has been a tremendous amount of effort expended in understanding the electromagnetic shower and hadronic cascade phenomena, and a good knowledge of these phenomena now exists.I However, the practical design of a calorimeter for a specific application usually reveals gaps in this knowledge, especial.ly in regard to hadron rejection in an electromagnetic shower calor imeter. A versatile shower aounter based on a leadscintillator sandwich design was constructed and tested in order to determine the optimal design for hadron rejection in an electromagnetic shower detector which will be used in Fermilab Experiment 605.

A Study of Some Properties Which Determine the Resolution of a Lead-Scintillator Sandwich Electromagnetic Shower Detector

Using the 10-50 GeV test beam at Fermilab we have studied the resolution of a lead-scintillator sampling shower counter system as a function of energy, sampling thickness, and photostatistics to confirm a design formula (¿/E)2 = at/E + 1/N + other contributions, where t is the thickness of a sample measured in radiation lengths, N is the number of photoelectrons, ¿ is the rms energy resolution, and E is the incident energy.