D.E. Yount

ENERGY RESOLUTION OF A MULTIWIRE PROPORTIONAL QUANTAMETER.

Abstract The energy resolution and certain other characteristics are evaluated for an electromagnetic-shower detector consisting of multiwire proportional chambers interleaved between lead plates. Such a detector preserves the energy linearity, angular isotropy, and position uniformity of the standard ion-chamber quantameters used in monitoring photon beams, and in addition, it can determine the point of incidence, the time of arrival, the detailed spatial shower development, and the total energy of individual gamma rays. The energy resolution is, however, significantly broader than for the corresponding shower counter in which plastic scintillators are used between lead plates. This can be understood in terms of a simple model that takes into account fluctuations in ionization in the thin detector planes as well as fluctuations in the number of shower tracks sampled.

Inclusive

We have measured inclusive ..gamma.. and ..pi../sup 0/ production in multiprong events produced by e/sup +/e/sup -/ annihilation in the center-of-mass energy range 4.9 to 7.4 GeV. We find that ..pi../sup 0/ inclusive cross section to be consistent in shape and normalization with half the charged-..pi.. cross section between chi = 0.15 and 0.60, with an integrated inclusive cross-section ratio of sigma (..pi../sup 0/)/ vertical-bar (sigma (..pi../sup +/) + sigma (..pi../sup -/) vertical-bar = 0.47 +- 0.10.

\gamma

Abstract A method is described for constructing and operating multi-wire proportional chambers having systematic gain variations of less than ±2% rms over their entire active area.

and

Abstract Test data are summarized for a muon identifier consisting of iron absorber plates followed by multiwire proportional chambers. Because of the penetrating secondaries that result from hadronic interactions, conventional muon identifiers lacking spatial resolution require many collision lengths to attenuate, and thus to separate incident hadrons from muons. By using multiwire proportional chambers, hadronic interactions can be detected well before the subsequent hadron cascades have been fully absorbed. This permits a substantial reduction in absorber thickness and is important in applications in which the muons originate in a large volume or in which they are to be identified over a large area or large solid angle. A typical result from these tests is that at 3 GeV/c a single multiwire proportional chamber, following only 50 cm of iron, can reject pions with 96±1% efficiency while accepting 96% of the incident muons. An important advantage of this technique is that the performance is expected to be rather independent of energy above a few GeV.

\pi^0

Abstract We have searched for relativistic, highly-interacting fractionally-charged particles using the free-quark detector at the e + e − storage ring PEP. No convincing events were seen. For an assumed interaction cross section with matter of 100 times geometric, 90% confidence level upper limits on their production relative to e + e − → μ + μ − are between 0.025 and 0.49 depending on quark mass (up to 13 GeV/ c 2 ) and reaction type. These are the first published limits on the production of fractionally charged particles with interaction cross sections of 100 times geometric or larger.

Production in

Abstract We report the results of a search for fractionally charged particles in e + e − reactions at a center of mass energy of 29 GeV. We find no evidence for such particles and present upper limitts on R q = σ q q X/σ μμ for change 1 3 e and 2 3 e which range from 1 to 8 × 10 −2 for mass up to 12 GeV/ c 2 .

e^+ e^-

We have measured inclusive ..gamma.. and ..pi../sup 0/ production in multiprong events produced by e/sup +/e/sup -/ annihilation in the center-of-mass energy range 4.9 to 7.4 GeV. We find that ..pi../sup 0/ inclusive cross section to be consistent in shape and normalization with half the charged-..pi.. cross section between chi = 0.15 and 0.60, with an integrated inclusive cross-section ratio of sigma (..pi../sup 0/)/ vertical-bar (sigma (..pi../sup +/) + sigma (..pi../sup -/) vertical-bar = 0.47 +- 0.10.

Annihilation

Abstract We present measurements of the cross section for inclusive D and K meson production in e+e− annihilation in the center of mass energy range 3.6 to 5.8 GeV. D production accounts for most of the increase in the total cross section for hadron production in e+e− annihilation at energies above 4 GeV.

MULTI-WIRE PROPORTIONAL CHAMBERS WITH UNIFORM GAIN

Abstract Specifications and test data are given for a lead-scintillator electromagnetic shower counter used to detect beam photons at Fermi National Accelerator Laboratory. The response is independent of beam position to ±1.4% rms over a 25 cm × 25 cm area. Shower penetration losses reach 4.1% at 250 GeV but are easily calculable. The resolution is limited almost entirely by fluctuations in the number of shower tracks sampled: The full-width-at-half-maximum is approximately 43%/E 1 2 , where E is the incident energy in GeV.

Muon Identification Using Multiwire Proportional Chambers

Abstract The development of a sparkostrictive wire-chamber spectrometer is described. The spectrometer consists of 9 chambers ranging in active width-times-height from 91 cm × 81 cm to 152 cm × 91 cm. The chambers are positioned between the 152-cm-diameter pole faces of the Lawrence Berkeley Laboratory M5 magnet, which has a 120-cm gap and a 6-kG field in this application. The grid wires are spaced 1 mm apart and on most chambers are oriented with wires running vertically and at ±30° angles to the vertical to provide three redundant coordinates per track. The root-mean-square spatial resolution is typically 1.6 mm. The chambers, while capable of one-track efficiencies of virtually 100% and three-track efficiencies averaging better than 98% per track, are extremely delicate and require constant attention. The various steps taken to achieve high efficiencies are analyzed, and the performance during a recent K e 4 + −K π ee + experiment involving more than 1.6 × 10 6 triggers is evaluated.