The detection of low-energy charged particles with particle identification up to 3. 5 GeV/c

Abstract

A reasonablytouipact apparatus employing solenoid fields, Gerenkov counters, drift chambers, and time-of-flight capabi ties is described. Good particle identification can be obtained through J combination of time-of-flight information and Cerenkov thresholds fo n, k, p up to about 3.5 GeV. I. Central Detector for Momentum Measurement and la-tification of Low Momentum Hadrons. iVe use here an ordinary solenoid type detector provic g a longi tudinal field. This will need compensating coils to get a /B-dS.=o along the beam. Here the stress is put on low momentum particles with good separation of n, K, P rather than a specially good momentum resolution. This would be needed to make an exact energy momentum balance which, in any case, would be very difficult with a total energy of 30 GeV. Instead of a plain solenoid, one can think of Helmholtz coils,with the difficulty that the field is no longer uniform which makes track recognition more difficult. On the other hand, it provides free space which can be useful for neutral detection. *•*.. The setup , which is described here, (figure 1 and 2), deals with Wl*> detection of charged particles. One can add a neutral detector outside ^5s which would provide a complete determination of the multiplicity over the solid angle. Nevertheless, the inside radius of this detectoT for neutrals would be 1.4 m which makes it rather expensive.

Phase equilibria in the ZrO2–GdO1.5 system at 1400–1700°C

“…The GdO 1.5 -rich phase boundary shifts from 69.9 to 76.5 mol% GdO 1.5 with increasing temperature (1450-1800 • C). The solubility of ZrO 2 in the monoclinic B-type modification of GdO 1.5 (B) does not exceed 2 mol% [3,6,18]. The literature data on the phase boundaries T/(T + F), (T + F)/F, F/(F + C) and (C + B)/B are in good agreement.…”

“…Phase diagram studies of the system ZrO 2 -GdO 1.5 have been performed by Perez y Jorba [3], Lefevre [4], Rouanet [5,6], Negro and Amato [7], Scott [8] and Uehara et al [9] by using X-ray diffraction (XRD) and thermal analysis. In addition, particular phase equilibria have been investigated with the X-ray diffraction, Raman and Mössbauer spectroscopy, pertrographic analysis as well as the electron probe microanalysis in the limited temperature and/or composition ranges [10][11][12][13][14][15][16][17][18][19][20][21].…”

“…The invariant reaction T ⇔ M + F, which corresponds to the eutectoid decomposition of the tetragonal phase was found to occur at 1140-1145 • C [7]. The cubic fluorite-type phase Zr 1 − x Gd x O 2 − x/2 (F) is stabilized in a wide range of composition and temperatures [3,4,6,8,12,15]. It coexists with the tetragonal phase on the zirconia-rich side and with the solid solution based on C-type modification of GdO 1.5 (C) on the gadolinia-rich side [8,18].…”

“…Within the F-phase domain, an ordered superstructure of the fluorite structure is formed at low temperatures, which is called pyrochlore-type phase (P) [3,9,10,17,18,22]. The general formula of the pyrochlore structure can be written as A 2 B 2 O 6 O .…”

Synthesis, characterization and lattice thermal expansion of some compounds in the system Gd2CexZr2−xO7

“…It may be noted that Gd 2 Zr 2 O 7 exists as a disordered fluorite phase at high temperature whereas it has an ordered pyrochlore crystal structure at lower temperatures in which the cations, and the oxygen vacancies are ordered [16]. It shows order-disorder transition at comparatively high temperature of about 1550 • C [17].…”