[en] This paper describes an experimental search for GUT magnetic monopoles in the MACRO experiment using the nuclear track subdetector CR39. After discussing the working principle, the charge resolution and the calibration of the detector, the experimental procedure for searching for magnetic monopoles is described. Since no candidates were found, the upper flux limits obtained by the MACRO CR39 used as a 'stand alone detector' for magnetic monopoles of different magnetic charges are presented

[en] We present new calibrations of different production batches (from 1989 to 1999) of the INTERCAST CR-39, using the BNL-AGS 1 A GeV iron beam. The comparison with previous results, obtained with the 158 A GeV lead beam from the CERN-SPS shows that, while each production batch has a different calibration curve (mainly due to minor differences in the production conditions), the aging effect is negligible. We also tested the dependence of the CR-39 response from the time elapsed between exposure and analysis (fading effect). The fading effect, if present, is less then 10%. It may be compatible with the experimental uncertainties on the bulk etching rate v_B

[en] We present the results of an experimental work aimed at improving the performances of the CR-39[reg] (Registered Trademark of PPG Industries Inc.) nuclear track detector for neutron dosimetry applications. The work was done in collaboration with the Intercast Europe S.p.A., producer of CR-39 for commercial and scientific applications. We compare the CR-39 made with different additives concentrations and different polymerization processes. We evaluate the response of the CR-39 to fast neutrons from three sources: ²⁴¹Am-Be, ²⁵²Cf and ²³⁸Pu-Li. Particular attention was paid to background fluctuations that limit the lower detectable dose

[en] Six stacks of CR39 [(C₁₂H₁₈O₇)_n, a Registered Trade Mark of PPG Industries, Inc.] nuclear track detectors with different targets were exposed to a lead ion beam of 158 A GeV at the CERN-SPS, at normal incidence, in order to study the fragmentation properties of ultra-relativistic lead nuclei. Measurements of the total, break-up and pick-up charge-changing cross sections of 158 A GeV Pb ions have been made for the first time

[en] We report the measurement of the fragmentation cross sections in high-energy nucleus-nucleus collisions using the 158 A GeV Pb⁸²⁺ beam from the CERN-SPS. The fragments have charges changed from that of the incident projectile nucleus by ΔZ=Z_Pb-Z_frag, with 8≤ΔZ<75. The targets range from polyethylene to lead. Charge identification is made with CR39 nuclear track detectors, measured with an automatic image analyzer system. The measured fragmentation cross sections are parameterized with an empirical relation in terms of the atomic mass of the target, and of the charge of the final fragment

[en] Six stacks of nuclear track detectors (CR39 and Makrofol) were exposed to 158 AGeV ²⁰⁷Pb ions at the CERN-SPS. The main purpose of the experiment was the calibration of the CR39 nuclear track detector used in a large area experimental search for magnetic monopoles at the Gran Sasso laboratory (the MACRO experiment). Different targets (C, CH₂, CR39, Cu and Pb) were used in order to study also the fragmentation properties of ultrarelativistic lead nuclei. The exposures were performed at normal incidence and at a density of about 2000 ions/cm². The total number of lead ions in a stack was about 5.8 x 10⁴. For the stack with the lead target, we measured the base area and the length of the etched cones. We obtain a unique calibration curve for the charge region 7 ≤ Z ≤ 83 combining the two types of measurements. Using the cone length method, we obtain a charge resolution σ_z ≅ 0.19 e for Z = 82 ions using a single measurement in one face of CR39. (orig.)

[en] New measurements of the total and partial fragmentation cross-sections in the energy range 0.3 - 10 A GeV of Fe²⁶⁺, Si¹⁴⁺ and C⁶⁺ beams on polyethylene, CR-39 and aluminum targets are presented. The exposures were made at Brookhaven National Laboratory (BNL), USA, and Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. The CR-39 nuclear track detectors were used to identify the incident and survived beam ions and their fragments. The total fragmentation cross-sections for all targets are almost energy independent while they depend on the target mass. The measured partial fragmentation cross-sections are also discussed.

[en] The nuclear track detector CR39 was calibrated with different ions of different energies. Due to the low detection threshold (Z/β∼6e) and the good charge resolution (σZ∼0.2 for 6e≤Z/β≤83e with 2 measurements), the detector was used for different purposes: (i) fragmentation of high and medium energy ions; (ii) search for magnetic monopoles, nuclearites, strangelets and Q-balls in the cosmic radiation.

[en] Three stacks of plastic CR-39 Nuclear Track Detectors (NTD) were exposed to 158 A GeV ²⁰⁷Pb ions at the CERN-SPS beam facility. The main purpose of this experiment was the calibration of the CR-39 for the search of atmospheric magnetic monopoles. Different targets (Al, Cu and Pb) were used to produce a large spectrum of charge ions for the purpose of calibration as well as the study of ultrarelativistic lead ion fragmentation. The exposure of each stack was performed at normal incidence with a fluence of about 1500 ion/cm². The total number of lead ions in each spill was about 7.8x10⁴ and there were eight spills incident on each stack. For the stack with the Cu target, the lengths of etched cones on one face of the CR-39 were measured. >From this measurement procedure, a new calibration curve has been generated for the extended charge region 63≤Z≤83. The charge resolution (σ_Z) achieved by this technique is ∼0.18e-0.21e

[en] More than 35 million high-energy muons collected with the MACRO detector at the underground Gran Sasso Laboratory have been used to search for flux variations of different nature. Two kinds of studies were carried out: a search for the occurrence of clusters of events and a search for periodic variations. Different analysis methods, including the Scan Statistics test and the Lomb-Scargle spectral analysis have been applied to the data. The seasonal modulation was confirmed. The signals at the positions of solar diurnal and sidereal modulations are confirmed, even if with smaller significance. No other deviations from the expected distributions were found