Bogdan C. Maglic

Acoustic spark chamber

Abstract Positions of the tracks produced by cosmic rays in a 15-kV four gap spark chamber were determined by measuring the time of flight T of the shock waves produced by sparks in argon. A pair of acoustic probes, using barium-titanate piezoelectric transducers is placed in each gap of the spark chamber. Times, T 1 i, in >sec for each probe i , are measured by a time-sorter and printed 2 sec after the passage of the particle through the chamber; from these, the position and the angle of the track was reconstructed by a program. With the spark energy of 2 joules, signals of the order of 1 V are obtained from the transducer. These signals are of N-wave form, with the rise-time of 1 >sec or less. The full width one-dimensional resolution in the spark position is 0.33 mm up to a distance of 52 cm; and 0.41 mm at 1 meter (giving an accuracy to 1:2500). The full-width spatial resolution, measured with three probes per gap is 0.8 ± 0.4 mm. The time-of-flight vs distance dependence is linear up to 2 meters. The recovery time of the probes is 10 >sec, suggesting the possibility of handling up to ten tracks during a long-spill accelerator pulse, with two probes per gap; and up to 20 with six probes per gap.

The sonic spark chamber and some of its experimental aspects

Efforts to make spark chambers in which the sparks are located by sound are reviewed brie fly. Advantages and limitations of this type of chamber are pointed out. (A.G.W.)

Search for baryon resonances up to 10 GeV mass produced in p+p->+mm with a resolution of +- 25 MeV

A simple magnet-less missiong-mass experiment is proposed to investigate the mass-spectrum of non-strange baryons of isospins 1/2 and 3/2 in the mass-range from 4 to 10GeV with a resolution of {+-}25 MeV or better. The spacing between baryons expected from the empirical interval rule {Delta}M{sup 2} = 1 BeV{sup 2} is 125 and 50 MeV for masses of 4 and 10 GeV respectively; if the rule holds, one expects 10{sup 2}-4{sup 2} = 84 resonances in this range. They plan to use the reaction p + p - p + MM and to detect the recoil protons in the region of the Jacobian peak. The protons of momenta from 400 to 850 MeV/c are selected by means of time-of-flight, range, and pulse height and are recorded in a pulse height analyzer. Since no magnets, wire planes, computers or any other major facilities are needed, the experiment can be done as soon as the beam, either full extracted (Option 1) or secondary diffracted (Option 2) or interla (Option 3) is available.