J. Moromisato

Design, construction, prototype tests and performance of a vertex chamber for the MAC detector☆

Abstract The design considerations, construction techniques, prototype tests and performance characteristics of a pressurized drift chamber used in the MAC detector at PEP are described. The chamber consists of 324 aluminized mylar tubes of 6.9 mm diameter with wall thickness of 100 μm. With appropriate shielding it operates successfully at 4.6 cm from the beam line. It was simple to construct and was configured to permit any malfunctioning tubes to be remotely disconnected without affecting operation. The chamber operated without problems for two years in the PEP environment with a gas mixture of 49.5% argon, 49.5% CO 2 , 1% CH 4 , at 4 atm absolute pressure. The mean spatial resolution averaged over all tubes was 45 μm. The time to distance relation for this gas mixture, along with the geometric positioning of individual wires relative to the central tracking chamber, was obtained with data from Bhabha scattering events. We also describe resolution studies performed with a prototype chamber in a SLAC test beam. A wide range of gases, gas pressures, and electronic parameters were explored. These studies proved that resolutions in the 10–50 μm range were possible. Our experience demonstrates that chambers of this type provide high precision tracking and are particularly suited for operation in regions with difficult physical access and/or high ambient radiation levels.

Results from a test of a PbCu liquid argon calorimeter

Abstract Results from a test with a lead-copper calorimeter in liquid argon are presented. The electromagnetic energy resolution obtained is 10%/√E. For hadronic showers the software weighting technique is demonstrated to work. A hadronic energy resolution of 50%/√E is found.

Performance of a PbCu liquid argon calorimeter with an iron streamer tube tail catcher

A lead-copper calorimeter in liquid argon and an iron streamer tube calorimeter acting as a tail catcher have been tested with pions in the energy range of 30–230 GeV. Results are given on the energy resolution, on sampling fluctuations and on the space resolution of the liquid argon calorimeter. For the combined system an energy resolution of σE ≈ 0.5√E is obtained applying software weighting techniques and corrections for the dead material between the two calorimeters on an event to event basis. The remaining tails in the energy distributions are discussed.

Nonflammable gas mixtures for streamer tubes

Abstract Tests with streamer tubes of small cross section (Frascati type) were performed using gas mixtures of isobutane, CO 2 , and small amounts of either Ne or Ar. The flammabilities of the various mixtures were experimentally determined. The operating characteristics of the streamer tubes with such mixtures were studied. It was found that the nonflammable mixture whose isobutane: Ne: CO 2 ratio is 10:2:88 gave an efficiency plateau of about 400 V with a midpoint at 4.9 kV.

Dimuon production by protons in Tungsten

The mass spectrum of dimuons produced by 400 GeV/c protons in Tungsten has been measured for masses greater than 7 GeV. A clear resonant signal of 2700 upsilons has been seen. The dependence of dimuon production on xF and pT has been determined for dimuon masses in the range 7.0 to 8.25 GeV as well as for masses in the upsilon region 8.25 to 9.75 GeV.

Measurements of Missing Mass (MM) Spectra from π−p ⇒ (MM)−p at 8, 11, 13.5, and 16 GeV

Measurements of missing mass (MM) spectra from π − p ⇒ ( MM ) − p at 8, 11, 13.5, and 16 GeV are reported. The MM mass range examined is 0 ≤ M 2 ≤ 7.3 GeV 2 with t (the proton four momentum transfer squared) in the interval 0.2 ≤ ∣ t ∣ ≤ 0.3 GeV 2 . Narrow resonances (R1, R2, R3, S, T, and U) with cross sections and widths reported by the CERN missing mass group are ruled out by the data. The cross sections d 2 σ/ dtdM 2 show evidence for triple factorizability of the form d 2 σ dtdM 2 ≃ D ( P B ) A ( M 2 ) G ( P ⊥ 2 ) where P B is the incident beam momentum,and P ⊥ 2 is the perpendicular component of the detected protons momentum with respect to the beam direction.

Measurements of Missing Mass (MM) Spectra from π−p ⇒ (MM)−pat 8, 11, 13.5, and 16 GeV

Measurements of missing mass (MM) spectra from π − p ⇒ ( MM ) − p at 8, 11, 13.5, and 16 GeV are reported. The MM mass range examined is 0 ≤ M 2 ≤ 7.3 GeV 2 with t (the proton four momentum transfer squared) in the interval 0.2 ≤ ∣ t ∣ ≤ 0.3 GeV 2 . Narrow resonances (R1, R2, R3, S, T, and U) with cross sections and widths reported by the CERN missing mass group are ruled out by the data. The cross sections d 2 σ/ dtdM 2 show evidence for triple factorizability of the form d 2 σ dtdM 2 ≃ D ( P B ) A ( M 2 ) G ( P ⊥ 2 ) where P B is the incident beam momentum,and P ⊥ 2 is the perpendicular component of the detected protons momentum with respect to the beam direction.

Measurements of Missing Mass (MM) Spectra from

Measurements of missing mass (MM) spectra from π − p ⇒ ( MM ) − p at 8, 11, 13.5, and 16 GeV are reported. The MM mass range examined is 0 ≤ M 2 ≤ 7.3 GeV 2 with t (the proton four momentum transfer squared) in the interval 0.2 ≤ ∣ t ∣ ≤ 0.3 GeV 2 . Narrow resonances (R1, R2, R3, S, T, and U) with cross sections and widths reported by the CERN missing mass group are ruled out by the data. The cross sections d 2 σ/ dtdM 2 show evidence for triple factorizability of the form d 2 σ dtdM 2 ≃ D ( P B ) A ( M 2 ) G ( P ⊥ 2 ) where P B is the incident beam momentum,and P ⊥ 2 is the perpendicular component of the detected protons momentum with respect to the beam direction.