A test is made of the recombination model proposed by Thomas \et [Phys. Rev. A 38 (1988) 5793] for the energy resolution, of which the experimental value is far worse than that estimated by the Fano theory, in liquefied rare gas detectors. The energy resolution and the charge collection based on the recombination model are calculated for electrons or gamma rays in the liquid chamber doped with photoionizing molecules. The calculated energy resolution does not agree with that obtained by the recent experiments, although the agreement is good for the charge collection. It is suggested that the recombination is not a main cause of the energy resolution. Possible causes of poor energy resolution are discussed.
A new observation of low energy cosmic ray particles with the energies from 4 to 120 MeV/n by the HEP instrument onboard the GEOTAIL satellite orbiting at 1 AU shows a remarkable enhancement of anomalous cosmic ray (ACR) N, O and Ne in the period September 1992–December 1993 before approaching to the solar minimum in solar cycle 22. The ACR fluxes obtained by the GEOTAIL observation are in good agreement with the results earlier obtained from the SAMPEX satellite [Mewaldt et al. 1993a,b]. The ACR carbon is also evident though the C enhancement is small compared with those of N, O and Ne. We confirm the new SAMPEX finding that the ACR fluxes have recovered more rapidly in 1992–1993 than in previous solar cycles and find this tendency continues to the end of 1993.
A series of corotating energetic helium events with 3–5 MeV/n has been observed by the HEP telescopes onboard the GEOTAIL satellite at 1 AU from October 1993 to August 1994. We have examined the relationship between solar wind (SW) speeds observed at 1 AU and the intensity of He in the series of the corotating interaction region (CIR) events. The speed difference of the high-speed SW from slow-speed SW, which forms a CIR in the outer heliosphere, shows a reasonable correlation with the peak intensity of He at 3–5 MeV/n. The speed difference of those SWs is considered to be related to the shock strength which develops in a CIR at a distance from the Sun. Such a correlation between energetic ions associated with CIRs and SW speed has not been shown so far for the events during the period of 1978-1986. We have also investigated the dependence of the relation between the CIR ion events and the SW speeds during the period between 1978 and 1995 which corresponds to the high solar active phase of Solar Cycle 22. There is a good correlation between the SW speed and the peak intensity of CIR energetic ions in the quiet phase of solar activity, but not in the active phase.
A method for the calculation of the energy losses of heavy charged particles in a low energy region (<1 MeV/nucleon) for the plastic nuclear track detectors is described. The method is based on the fundamental relation (dE/dx)ion=(Zeff/γp)2(dE/dx)proton (Zeff and γp are the effective charges of heavy ion and proton, respectively). Firstly, the stopping power of a given plastic detector for the proton is obtained from the atomic stopping powers of the individual constituent elements for the proton, which are derived from the existing data for other organic compounds in solid state, assuming the Bragg's additivity rule. Then, the energy loss rates of heavy ions in the plastic detectors have been calculated from the above relation, using the formulas for the effective charges. The range-energy relations, obtained by this method, for fission fragments in polycarbonate resin and cellulose triacetate are in good agreement with the experimental results.
The isotope identification with the solid-state track detector (SSTD) newly developed for the observation of heavy cosmic ray particles was performed using 56Fe and 55Fe ions with 460 MeV/nucleon. Mass resolution for iron isotope was thus improved to ~ 0.20 amu in rms. The high speed automatic system of microscope analyzer was also developed to scan and analyze tracks formed by heavy ions in SSTD. The combination of isotope telescope consisting of SSTD with the high speed scanning system enables us to realize a large-scaled observation for trans-iron galactic cosmic rays (GCRs).
In order to obtain an economical design of the strong-focusing synchrotron magnet, the pole shape on the low field side is systematically investigated by the aid of a resistance network analogue. The results show that there exists an optimum condition of minimizing the low field side margin for a simple pole shape. The application of the condition to the practical cases is discussed.
