Kimiaki Masuda

Inclusive production of π0'S in the fragmentation region at the SppS collider

Abstract The inclusive production of π0s has been measured in the nucleon fragmentation region at the S p pS Collider at 630 GeV center of mass energy. Average transverse momentum and rapidity distributions compared with lower energy ISR data show no sizable violation of Feynman scaling in the fragmentation region.

Proportional counter filled with highly purified liquid xenon

Abstract The electron avalanche in highly purified liquid xenon is observed with reproducible gain. The electronegative ion pumping is effective for suppressing spurious discharges rather than for purifying liquid xenon.

A liquid xenon proportional scintillation counter

Abstract The characteristics of a liquid xenon proportional scintillation counter have been studied by using conversion electrons from 207 Bi. Pulse shapes of the induced charge and the scintillation in the ionization chamber mode were observed and the variations of relative photon yield of the proportional scintillation against the applied voltage were measured. The energy spectra of the proportional scintillation for 207 Bi were compared with those of the charge. The best resolution of the proportional scintillation was about 18% fwhm for 1 MeV electrons, which was almost the same as that of the charge. The linear relation between the normalized photon yield at constant electric field strength on wire surface and wire radius as expected from analogy with gas was not obtained but the tendency of increase in the normalized photon yield for wire radius was confirmed.

Test of a dual-type gridded ionization chamber using liquid xenon

Abstract A liquid xenon dual-type gridded ionization chamber designed as a gamma-ray spectrometer was constructed and some tests for gamma-rays were made by using highly purified xenon gas. The energy resolution of 8.6% at fwhm was obtained for collimated gamma-rays of 662 keV. The resolutions at fwhm for non-collimated gamma-rays were (9.6 ± 0.4)% at 662 keV, (6.5 ± 0.3)% at 1332 keV and (4.5 ± 0.3)% at 2614 keV. These results show that, for gamma-ray energies above 1600 keV, the energy resolution for the liquid xenon ionization chamber is better than that for a conventionally available 1 3 4 ″ diameter × 2″ NaI(Tl) crystal. This characteristic of the chamber was kept nearly constant for more than 24 h. The resolution obtained experimentally were compared with the theoretical values and the causes of the differences between them are discussed.

SCINTILLATION YIELDS BY RELATIVISTIC HEAVY IONS AND THE RELATION BETWEEN IONIZATION AND SCINTILLATION IN LIQUID ARGON

Abstract Scintillation yields per unit energy deposited by relativistic heavy ions in liquid argon have been measured. They are (1.41 ± 0.07) for 613 MeV/n Ne ions and (1.39 ± 0.07) for 705 MeV/n Fe ions, if the value is normalized to unity for 5.3 MeV alpha particles. These results show that the scintillation intensity for relativistic heavy ions in liquid argon is proportional to the deposited energy, that is, to Z 1 2 , where Z 1 is the nuclear charge of heavy ions. Furthermore, the variation of ionization and scintillation in liquid argon has been investigated as a function of electric field using relativistic Ne and Fe ions. It is shown that a linear combination of ionization signal I and scintillation signal S , I + aS , is proportional to the deposited energy, independently of electric field strength and types of incident particles. This suggests that if we use both signals, we may construct a massive calorimeter that can be used for nuclear reactions induced by relativistic heavy ions.

Ionization and scintillation produced by relativistic Au, He and H ions in liquid argon

Abstract We have measured ionization and scintillation produced by relativistic ions of Au, He and H in liquid argon. The sum of ionization signal and scintillation signal per unit energy deposition is the same for He and H ions, which is also the same as that for relativistic Ne, Fe and La ions previously measured. We have found that quenching occurs when liquid argon is irradiated by relativistic Au ions and that the sum per unit energy deposition for the Au ions is 70–76% of that for the other ions mentioned above.

Let dependence of the luminescence yield from liquid argon and xenon

Abstract The relative luminescence yield by excitation of α particles, fission fragments and internal conversion electrons in liquid argon and xenon have been measured. A reduction of luminescence yield due to fission fragments is observed. The ratios of the luminescence intensities per unit energy deposit due to light and heavy fission fragments to the luminescence intensity due to α particles are 0.244±0.005 and 0.232±0.005, respectively, for liquid argon, and those for liquid xenon are 0.30±0.01 and 0.31±0.01, respectively. The luminescence yield for liquid xenon is estimated to be 1.4±0.2 times that for liquid argon under α particle excitation.

Estimation of the electron lifetime in tetramethylsilane

Abstract The variation of the collected charge with electric field in a diode-type ionization chamber is used to estimate the electron lifetime in tetramethylsilane (TMS). The primary ionizing particles are the 976 keV conversion electrons emitted from a 207 Bi source. In the best purity sample of TMS we obtained an electron lifetime of 11 ± 2 μs which corresponds to an attenuation length at 10 kV/cm, equal to 11 cm. The free ion yield at zero electric field, G f (0), is determined to be 0.51 ± 0.05.

A liquid xenon position sensitive gamma-ray detector for positron annihilation experiments☆☆☆

Abstract A liquid xenon position sensitive gamma-ray detector for positron annihilation experiments has been constructed. The detector is a single wire drift chamber filled with liquid xenon and consists of a drift space for electrons whose sensitive volume is 50 mm × 50 mm × 10 mm thick, and a single wire proportional counter forddetection of the drifted electrons. The incident position of gamma-rays is determined by measuring the time interval between the direct scintillation due to electrons produced by gamma-rays and the proportional scintillation initiated by drifted electrons near the anode wire of the proportional counter. The intrinsic spatial resolution of 0.6 mm at fwhm was achieved for collimated 662 keV gamma-rays with a high detection efficiency.

A 4-inch silicon/tungsten calorimeter for p-p collider experiments

Abstract A 4-inch diameter silicon/tungsten sandwich calorimeter with 64 cm 2 in active area and 18 radiation lengths in depth has been constructed. The performance has been investigated for incoming electrons of 500 MeV to 4.5 GeV. The calorimeter shows a good linearity over the electron energy region and the energy resolution is well expressed by σ (rms)/ E = 17√ t / E %, where t represents the unit sampling thickness in radiation lengths and E the incident electron energy in GeV. The agreement between these results and a Monte Carlo simulation is quite satisfactory. The center of shower has been determined with the accuracy of better than 2 mm at energies exceeding 1 GeV.