|INFN Sezione di Roma 2|
|Universita' di Roma Tor Vergata"|
The Cosmic AntiParticle Ring Imaging Cherenkov
Experiment (CAPRICE) flew for the first time in a balloon
for 27 hours in August 1994 (CAPRICE94). It
about more than 6 million cosmic ray particles and the
measure the amount of antimatter in the cosmic radiation
way [see the web site for references and publications].
of the experiment is to measure the flux of antiparticles
(antiprotons and positrons) in the cosmic radiation. The result
give valuable information on the production and transport
cosmic rays in our galaxy. In addition one might find exotic
of antimatter, others than the expected secondary
production from cosmic ray nucleon interaction with the
interstellar gas. Any excess of antimatter can come from
of dark matter particles, extragalactic origin, evaporation of
primordial black holes etc. We also continue the search
heavier antinuclei (antihelium, anticarbon etc.) which would be
direct evidence for the
existence of anti-stars. The flux of all light isotopes in
radiation gives valuable information about the production and
transportation mechanisms of cosmic rays in our galaxy. Besides
RICH detector the spectrometer includes a super conducting
a tracking detector system of drift chamber and
chambers, a time-of-flight system and an Si-W imaging
calorimeter. The CAPRICE97 experiment was successfully
on the morning of 24 May1997. All instruments worked well and
were recorded during the three hour long ascent to a float
36 km. The flight had to be terminated after four hours
CAPRICE98 was launched by balloon from Fort Sumner, New Mexico, on 1998 May 2. It floated at an atmospheric depth of about 5.5 g cm-2 for a period of 21 hr at a mean vertical cutoff rigidity of about 4.5 GV. More than 5 million triggers were collected at float altitude. A total of 31 antiprotons with a rigidity at the spectrometer between 4 and 50 GV were identified with small backgrounds from other particles. The absolute antiproton energy spectrum was determined in the energy region at the top of the atmosphere between 3.2 and 49.1 GeV. We found that the observed antiproton spectrum and the antiproton to proton ratio are consistent with a pure secondary origin. However, a primary component cannot be excluded.This experiment has reported the first mass-resolved high-energy antiprotons ever detected.
CAPRICE is one of the flights performed by the WiZard collaboration with members from France, Germany, Italy, Sweden and USA.
Schematic view of the CAPRICE98 apparatus.