Spark Chamber Spectrometer Research Articles

A study of the semileptonic decays of neutral kaons

Dalitz plots of 74 000 Ke30 and 150 000 Kμ30 decays have been investigated to measure the t-dependence of the form factors ƒ+(t) and ƒ(t) describing the vector contribution to the decay matrix element. The decays were registered by a wire spark chamber spectrometer in the neutral beam of the Serpukhov accelerator. An analysis using a linear expansion of the form factors gives the slopes: λe+=0.0306±0.0034 for the Ke30 decays and λμ+ = 0.0427±0.0044, λ0 = 0.0341± 0.0067 for the Kμ30 decays. The ratio of the form factors ƒ− to ƒ+ has been found to be ξ(0)=ƒ−(0)/ƒ+(0)=−0.10±0.09. These results are compared with the relevant theoretical models. Together with the data of other experiments in which the parameters of muon and electron interactions are measured, the observed difference between λ+μ and λ+e gives some indication of the violation of μ-e universality.

A study of the reactions [formula omitted] (backward) and [formula omitted] (backward) for kaon momenta between 1 and 8 GeV/c

We present results for the reactions K 0 p→Λπ + and K 0 p→∑ 0π +, for |u'| <0. 05 ( GeV/c) 2 and kaon momenta between 1 and 8 GeV/ c. The experiment was performed ina neutral beam at the PS with a two arm spark chamber spectrometer. The cross sections show strong dependence on beam energy and momentum transfer u′. Λ polarization is compatible with zero. We compare energy dependence of the backward cross sections with the baryon exchange model from π N scattering.

Coherent production of low-mass pπ +π −states in the interaction of 18.6 GeV/cprotons with 4He nuclei

A specially developed scintillator and spark chamber spectrometer has been used to measure recoiling 4He target nuclei, and a magnetic spark chamber spectrometer to measure forward-going pπ +π −particles, selecting coherent events by four-momentum balance. Two enhancements in the pπ +π −mass spectrum are found at 1.49 and 1.71 GeV/ c 2. The branching ratio of the quasi-two-body stateΔ ++π −is42 ± 8%in the 1.71 GeV/ c 2 mass region. The tslope, as a function of pπ +π −mass, is consistent with what can be predicted using the impulse approximation. The decay angular analysis indicates the presence of several interfering states in the 1.5 GeV/c 2mass region and of one state of spin3/2, possibly5/2, in the 1.7 GeV/c 2mass region. There is some preference shown for t-channelhelicity conservation. The data are very similar to results obtained with photon targets, which provides independent support for the hypothesis that vacuum exchange is dominant in the production of low-mass pπ +π −states in pp interactions around 20 GeV/c.

The small momentum transfer k L o C→K S 0 C regeneration at high energies

Results of the first elastic K S o regeneration experiment on carbon, using magnetic spark chamber spectrometer, are presented in the beam momentum interval 10≦p≦50 GeV/c. The d ifferentia cross section dσ/dt is reconstructed in the range 0·0025≦−t≦0·02 (GeV/c)2 and its slopeB is found to be momentum independent with an average valueB=(65±11) (GeV/c)−2. The results are in agreement with the calculations using the coherent production model.

Photoproduction of Φ-mesons at small t-values

The reaction γ + p → Φ + p has been measured using a spark chamber spectrometer and a tagged photon beam in the energy range from 4.6 to 6.7 GeV. Approximately 3500 photoproduced elastic Φ-events have been collected in the t-range between t min and t = −0.4 (GeV/ c) 2. Cross sections and t-distributions are presented.

Diffraction dissociation and Coulomb dissociation of high-energy neutrons by nuclei

We present the results of a spark chamber experiment in which we studied the reaction n + A → (p + π −) + A′, where the (p π −) pair is coherently produced off carbon, copper, and lead nuclei. Between 5 000 and 55 000 good events were collected with each target. Incident neutrons in the momentum range 10 to 28 GeV/ c were used. Forward-going (p π −) pairs from the above reaction were detected in a wire spark chamber spectrometer which measured the momentum and angles of each particle. The observation of a sharp forward peak (of width appropriate to the nuclear radius) indicated that a large fraction of the events were coherently produced. There is no evidence for any appreciable production of the well-established I = 1 2 nucleon isobars; our limits appear to be inconsistent with estimates based on a straightforward extrapolation of pp data. The lead data show evidence for coulomb production of the Δ (1236). The carbon data indicate a spin J ⩾ 3 2 for the coherently produced (p π −) states with pure J = 3 2 possible. We cannot draw any firm conclusions about helicity conservation. The Drell-Hiida-Deck model does not adequately fit the data, nor is the double-Regge-pole model completely satisfactory.

Search for Structure inπ−p→ΛK0atΣKThreshold

We have measured the cross section, the angular distribution, and the $\ensuremath{\Lambda}$ polarization for the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\Lambda}{K}^{0}$. A spark-chamber spectrometer was used to collect 8400 $\ensuremath{\Lambda}{K}^{0}$ events at fourteen beam momenta near $\ensuremath{\Sigma}K$ threshold. Our data do not show the prominent cross-section enhancement suggested by some previous experiments. However, detailed structure in the cross section and the angular distribution agrees well with a simple model which includes a cusp effect at $\ensuremath{\Sigma}K$ threshold.

Coherent regeneration in hydrogen from 3 to 10 GeV/c

We have studied the proper time distribution of coherent π + π − decays from a 3 – 10 GeV/ c K L o beam incident on a one meter liquid hydrogen target using a wire spark chamber spectrometer in the 3 0 neutral beam at SLAC. We find ∣(ƒ(0) − ƒ(0))/k∣ = 0.43 ± 0.11 mb , φ(ƒ(0) − ƒ(0)) = -101 0 ± 42 0 .

Search for an [formula omitted] isobar at 1.9 GeV/ c incident momentum in the reaction [formula omitted

We have obtained, using a spark chamber spectrometer, the π − missing mass spectrum in the reaction π + p → π − N ∗+++ at 1.9 GeV/ c for two emission angles of the π −. In order to study the possible production of an I= 5 2 isobar, we have calculated the contribution, to the missing mass spectrum of the OPE model of Ferrari and Selleri. This gives an upper limit of the order of 40 μb for the production of such an isobar.

Optical system for precision spark chamber spectrometer

Criteria, design and the performance of an optical system for a large spark chamber spectrometer capable of measuring momenta in the range of 300–1000 MeV/ c to about ±2% and the portion of sparks and fiducials in space to ± 1 2 mm is described. The system is equiped with a grid of fiducials made of electro-luminescent panels surrounding the spark chambers The spark location in space is obtained by interpolation between the local fiducials. The optical system has been stable during the course of a year and a half and showed no deterioration in the precision of locating sparks over that period.

A proposed apparatus for the measurement of the cosmic-ray muon momentum spectrum and charge ratio, and the investigation of muon interactions

The construction of a cosmic-ray spark-chamber spectrometer for use in the study of the charge ratio and interactions of muons at energies up to 3 000 GeV is proposed. The apparatus will consist of a stack of interleaved spark chambers and magnetized iron plates, placed at a depth of 250 m.w.e. underground in order to remove the low-energy component of the cosmic-ray muon flux. This report gives an appraisal of the design of the apparatus and summarizes its expected performance.

Thin Aluminum Foil Spark Chamber Spectrometer

A description of a thin aluminum foil spark chamber spectrometer is given. The magnet has two sets of slots to allow 90° stereo views for photography. A discussion is presented on its characteristics as well as its possible use for the measurement of high-energy γ rays.

Design and performance of an on-line wire spark chamber spectrometer for 5 to 30 GeV/c particles

This paper describes the design and performance of a wire spark chamber spectrometer system connected on-line to a PDP-6 computer. The system analyzes particles of 5 to 30 GeV/ c momentum scattered at angles from 0 to 15° with a momentum resolution of 0.5% and an angular resolution of 0.5 mrad. The chambers can be sparked every 1.25 msec and the computer can analyze up to 150 events in the 2 sec between AGS beam spills.

A Spark Chamber Spectrometer for Space Protons

A new radiation detector instrument system was conceived by one of us (R.M.) in 1962 to measure the spectra of energetic particles in space. A laboratory prototype of a flyable version of such an instrument system has now been constructed under contract to the Air Force Cambridge Research Laboratories. It has been designed to measure unidirectional proton spectra in six energy intervals between 21 Mev and 210 Mev. The system consists of a sealed, compact, six-channel spark-chamber of ceramic and metal construction and associated miniaturized circuits for coincidence triggering, high-voltage pulse generation and data readout. Geiger counter coincidence triggering detectors are arranged co-linearly with the spark chamber. The thicknesses of the plates in the spark chamber are designed so that the intervals in proton range give approximately equal spacings on a logarithmic scale of the proton energy. This spark chamber spectrometer instrument system has the following features: 1. It derives its energy determinations from range-energy relations which are fixed absolute constants for the measurement. 2. The experimental calibration constants such as the solid angle, the effective area, and the direction are common to all channels. 3. It provides digitized information directly in the form of large electrical pulses. 4. It has a detection efficiency of nearly 100 percent. 5. Power consumption is of the order of 1 watt. 6. It is compact and rugged in construction.