D.D. Reeder

Measurements of the proton-proton total cross section and small angle elastic scattering at ISR energies

Measurements of the total cross section have been performed at the ISR with c.m. energies between 23.5 GeV and 62.5 GeV. Two independent experimental methods have been applied, a measurement of total interaction rate and of small angle elastic scattering. Both experiments give consistent results showing that the total cross section increases by (11.8±1.5) % over the ISR energy range. This experiment has also measured the slope of the forward diffraction peak in elastic scattering at small momentum transfer. The elastic cross section shows the same relative rise as the total cross section, and the ratio λ of elastic to total cross section approaches a constant value of λ=0.178±0.003.

A liquid-scintillator total-absorption hadron calorimeter for the study of neutrino interactions

Abstract We describe the performance of a large-volume liquid-scintillator calorimeter which has been used to measure the total energy of hadrons produced by interactions of neutrinos with nucleons. The resolution of the calorimeter is about 12% rms for incident pions over the energy range 20–150 GeV, and about 15% for neutrino-induced hadron systems in the chosen fiducial volume after corrections for imperfect energy containment.

The properties of proton-proton interactions between 100 and 1000 GeV from a cosmic-ray experiment

Abstract Proton-proton interactions above 100 GeV have been studied in an experiment using cosmic-ray protons interacting in a liquid hydrogen target. From several hundred hydrogen interactions, it has been learned that: (a) the total inelastic pp cross section is not changing significantly with energy above 30 GeV; (b) the multiplicity distributions of charged prongs agree with a Poisson distribution in charged-particle pairs; (c) the average charged prong multiplicity increases as 1 n s ; (d) the angular distribution of charged particles agrees with a c.m. momentum distribution of charged particles that varies as exp exp [−8 p T 2 −8 x 2 ] d 3 p / E (where x = p L / p o ) and a nucleon distribution that varies as 10 x exp [−3 p T 2 ] d 3 p / E for 0.05

The Haleakala gamma ray observatory

A 10 m2 multi-mirror telescope for observing Cherenkov light signals from atmospheric cascades is now operating at Mount Haleakala, Maui, Hawaii. It differs from other atmospheric Cherenkov detectors in accepting pulses that originate from single photoelectrons, employing two sets of 18 optically independent phototubes in a logic system with nanosecond time resolution to reject ambient light from the night sky. With an angular aperture of 1.3 × 10−4 sr, cosmic ray showers are observed at a rate of ∼ 0.5 hz at the zenith, with nearly complete rejection of ambient light. This rate for hadronic showers implies an effective threshold near 100 GeV for electromagnetic showers. Two regions of the sky, one centered on the source and the other separated by from it by 3.6° are simultaneously monitored. Examples of observations of episodic and periodic (pulsar) sources are given.

Observation of short-lived particles produced in high energy neutrino interactions

Abstract Examination of a sample of 89 high-energy, neutrino-induced dilepton events produced in the Fermilab 15 ft bubble chamber has resulted in the direct observation of the production and visible semi-leptonic decay of short-lived particles. One charged decay, two neutral decays, and one decay candidate of undetermined charge are found. Assuming these events and the remaining dilepton signal result from D meson decays, we obtain τ D + = 2.5 −1.5 +3.5 × 10 −13 s and τ D 0 = 3.5 −1.7 +3.5 × 10 −13 s, using a maximum likelihood analysis.

Characteristics of a lead-scintillator calorimeter used to detect electron neutrinos

Abstract The response of a lead-liquid-scintillator calorimeter to electromagnetic and hadronic showers is reported. Operational characteristics, calibration, and the calculation of event energies are discussed. The hadronic resolution is measured to be 0.53 E ( GeV ) ; the electromagnetic resolution 0.27 E ( GeV ) . The charged current interactions of ν e have been identified by exploiting the difference in energy deposition along the beam direction for electron and hadron showers. The efficiency and effectivenes of the technique are discussed.

COSMIC RAY RESULTS ON THE A DEPENDENCE OF MULTIPLICITY AND ANGULAR DISTRIBUTIONS IN PROTON NUCLEAR INTERACTIONS ABOVE 100 GeV

Abstract A calorimeter-spark chamber system was used to collect data on several hundred proton-nucleus interactions above 100 GeV using targets of C, Al, Fe, Sn and Pb. The average charged prong multiplicity is found to depend on atomic mass number as 〈 n c 〉 = 〈 n c 〉(p-p) A x where x = 0.129 ± 0.004, with the dominant increase in multiplicity occuring in the backward (p-p c.m.) hemisphere. The value of x shows no significant energy dependence.

A large-area magnetic spectrometer for the study of high-energy neutrino interactions

Abstract We describe the design, construction, and performance of a large solid iron magnetic spectrometer which has been used to i dentify and measure the momentum of muons produced by interactions of neutrinos with nucleons. The rms momentum resolution varies from 10 to 15 percent between 5 and 150 GeV/ c .

Design features and test results of the CMS endcap muon chambers

Abstract Presented are the main design features and performance results of the Cathode Strip Chambers for the CMS Endcap Muon system. Although the strips are unusually wide (up to 16 mm ) for the cathode-to-anode wire distance of 5 mm , the six-plane structure of these chambers yields a spatial resolution of about 80 μm , essentially uniform and independent of the strip width. In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300 ns ) is obtained using a simple network of comparators. Time resolution achieved at the trigger level is ∼4 ns (rms) that allows unambiguous tagging of bunch crossings which occur every 25 ns . Aging test results, including those obtained with a recirculating gas system, are discussed; only minor aging affects were observed. The aging studies were performed with large-scale chambers; 700 m of wire were irradiated for a dose up to 0.4 C / cm of the total accumulated charge.

The Haleakala Gamma Observatory

The Haleakala Gamma Observatory is a 10m2 multi-mirror telescope for observing Cherenkov light from electromagnetic cascades in the atmosphere. It is situated at an altitude of 2950 meters at 20.7°N, 156°W on Mount Haleakala, Maui, Hawaii. It differs from most Cherenkov devices in accepting single photoelectron pulses. It employs two sets of 18 phototubes observing seperate regions of the sky to continuously monitor hadronic background. Hardware coincidence resolution is 10ns, and digital filtering can reduce this substantially, effectively eliminating random signals from ambient light. Events are timed to within ±2μs of UTC by a Cesium beam atomic clock. Hadronic showers are observed at rates of 0.5 to 0.7 Hz, implying a threshold for gamma-induced showers of about 200 GeV.