CRASH (Cosmic Rays And Strange Hadronic matter)

Developed by Istituto di Cosmo-geofisica, Torino / University of Tokyo

Balloon launched on 8/10/1995, from Base di Lancio Luigi Broglio, Trapani, Sicily, Italy

Purpose of the flight and payload description

CRASH was the acronym of Cosmic RAys and Strange Hadronic matter a balloon-borne experiment developed by a collaboration between the Istituto di Cosmo-geofisica from Torino, Italy and the University of Tokyo, Japan in early 1990s decade. It was specifically designed for the detection of the Strange Quark Matter, which according to theory is probably present in the cosmic-ray radiation at the top of the atmosphere.

The main characteristics of the instrument are shown in the figure at left (click to enlarge). The detection technique was based on the measure of the A/Z ratio of the nuclei crossing the detector. The charge, the velocity and the mass of the incoming nuclei were determined using both active and passive detectors.

S1 and S2 were diffusion-box-type scintillation counters used to measure the charge of incident particles with high accuracy. The discrimination threshold of the scintillators S1 and S2 was set during the flight at 7 minimum ionizing particle (MIP) in order to avoid protons and helium nuclei which are the most aboundant species in cosmic rays.

C1 and C2 were diffusion-box-type Cerenkov counters used to measure the velocity (i.e. energy/nucleon) of incident particles. The discrimination levels of the Cerenkov counters was set at 0.5 MIP in order to detect massive nuclei with Z=2.

S3, S4, S5 and S6 were light-guide-type scintillation counters used to measure changes in ionization energy loss of primary nuclei at different depths in the detector. Four double layers of multi-tube proportional counters were distributed along the detector in order to determine the trajectories of both primary and secondary particles with an accuracy of about 0.5 cm. The recording of an event was triggered by a threefold coincidence of scintillators S1, S2, and S3.

The passive detector was composed of three sections: 1) a stack of sandwiches of CR-39 plates and nuclear emulsion plates to measure the Z/beta ratio and the particle position, 2) a stack of emulsion and polyethylene plates for multiple-scattering observation (rigidity estimation) and 3) plates of Pb, tracking, emulsion and X-ray film to observe cascade development. The events were selected using the counter system located at the top of the instrument and then traced in the passive detector, where interactions of the primary particles were also observed in the passive detector.

The total weight of the instrument on its gondola was about 1500 kg.

Details of the balloon flight

Balloon launched on: 8/10/1995
Launch site: Base di Lancio Luigi Broglio, Trapani, Sicily, Italy  
Balloon launched by: Agenzia Spaziale Italiana (ASI)
Balloon manufacturer/size/composition: Zero Pressure Balloon 850.000 m3
End of flight (L for landing time, W for last contact, otherwise termination time): 8/10/1995
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 21 h 7 m
Landing site: In Munera, Albacete, Spain
 Payload weight: 1767 kg
 Overall weight: 2267 kg

External references

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