10 research outputs found
Nuclear Track Detectors. Searches for Exotic Particles
We used Nuclear Track Detectors (NTD) CR39 and Makrofol for many purposes: i)
Exposures at the SPS and at lower energy accelerator heavy ion beams for
calibration purposes and for fragmentation studies. ii) Searches for GUT and
Intermediate Mass Magnetic Monopoles (IMM), nuclearites, Q-balls and
strangelets in the cosmic radiation. The MACRO experiment in the Gran Sasso
underground lab, with ~1000 m^2 of CR39 detectors (plus scintillators and
streamer tubes), established an upper limit for superheavy GUT poles at the
level of 1.4x10^-16 cm^-2 s^-1 sr^-1 for 4x10^-5 <beta<1. The SLIM experiment
at the high altitude Chacaltaya lab (5230 m a.s.l.), using 427 m^2 of CR39
detectors exposed for 4.22 y, gave an upper limit for IMMs of ~1.3x10^-15 cm^-2
s^-1 sr^-1. The experiments yielded interesting upper limits also on the fluxes
of the other mentioned exotic particles. iii) Environmental studies, radiation
monitoring, neutron dosimetry.Comment: Talk given at "New Trends In High-Energy Physics" (experiment,
phenomenology, theory) Yalta, Crimea, Ukraine, September 27-October 4, 200
"Tomography" of the cluster structure of light nuclei via relativistic dissociation
These lecture notes present the capabilities of relativistic nuclear physics
for the development of the physics of nuclear clusters. Nuclear track emulsion
continues to be an effective technique for pilot studies that allows one, in
particular, to study the cluster dissociation of a wide variety of light
relativistic nuclei within a common approach. Despite the fact that the
capabilities of the relativistic fragmentation for the study of nuclear
clustering were recognized quite a long time ago, electronic experiments have
not been able to come closer to an integrated analysis of ensembles of
relativistic fragments. The continued pause in the investigation of the "fine"
structure of relativistic fragmentation has led to resumption of regular
exposures of nuclear emulsions in beams of light nuclei produced for the first
time at the Nuclotron of the Joint Institute for Nuclear Research (JINR,
Dubna). To date, an analysis of the peripheral interactions of relativistic
isotopes of beryllium, boron, carbon and nitrogen, including radioactive ones,
with nuclei of the emulsion composition, has been performed, which allows the
clustering pattern to be presented for a whole family of light nuclei.Comment: ISBN 978-3-319-01076-2. 55 pages, 28 figure
The preparation of large nuclear emulsion detectors and their application to the study of K-mesons and hyperons
Interactions of12C ions with emulsion nuclei at momentum 4.2 GeV/c per nucleon and the cascading-evaporation model
Effects of nutrient (N, P, C) enrichment upon periphyton standing crop, species composition and primary production in an oligotrophic softwater lake
Search for anomalous interaction mean free paths of charge, 2?Z?18 projectile fragments in emulsions exposed to 1.8 A GeV40Ar ions
Direct observations of galactic cosmic rays
The mysterious “radiation ... entering our atmosphere from above” discovered by Hess in 1912 is now known to be dominated by relativistic charged particles, mostly with energies in the GeV-range, but extending to energies higher by many orders of magnitude. As none of these particles can penetrate the earth’s atmosphere without interaction, detailed studies of their composition and energy spectra require observations with high-altitude balloons or spacecraft. This became possible only towards the middle of the 20th century. The direct measurements have now revealed much detail about the Galactic cosmic rays below 1015eV, but do not yet provide much overlap with the air-shower region of energies. A historic overview of the measurements is given, beginning with the realization that the majority of the cosmic rays are protons. The discovery and astrophysical significance of the heavier nuclei, and of the ultra-heavy nuclei beyond iron and up to the actinides, are then described, and measurements of the isotopic composition are discussed. Observations of the individual energy spectra are reviewed, and finally, the detection of electrons, positrons, and anti-protons in the cosmic rays, and the searches for exotic or unusual phenomena are summarized. Emphasis is given to the fact that all of these discoveries have become possible through the evolution of increasingly sophisticated detection techniques, a process that is continuing through the present time. The precise knowledge of the abundance distributions of the elements in the cosmic rays and of their isotopic composition permits a comparison with the “universal abundance scale” and provides strong constraints on the origin of the cosmic-ray material in the interstellar medium. “Clock-isotopes” reveal the time history of the particles. The shapes of the energy spectra of the individual cosmic-ray components are related to evolving ideas about particle acceleration and propagation in the Galaxy. In conclusion, prospects for future work are briefly discussed