An emulsion spectrometer has been built and tested with pion beams in a 0.7 T magnetic field. A momentum resolution, Δ P / P =13%±1%, has been obtained for 5 and 10 GeV /c particles.
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No description provided.
The energy loss spectrum of 150 GeV muons has been measured with a prototype of the ATLAS hadron calorimeter in the H8 beam of the CERN SPS. The differential probability dP/dv per radiation length of a fractional energy loss v = ΔEμ/Eμ has been measured in the range v = 0.01 ÷ 0.95; it is compared with the theoretical predictions for energy losses due to bremsstrahlung and production of electron—positron pairs or of energetic knock-on electrons. The integrated probability \(\int_{0.01}^{0.95}({\rm d}P/{\rm d}v){\rm d}v\) is (1.610 ± 0.015stat ± 0.105syst) · 10−3 in agreement with the theoretical predictions 1.556 · 10−3 and 1.619 · 10−3. Agreement with theory is also found in two intervals of v where production of electron-positron pairs and knock-on electrons dominates. In the region of bremsstrahlung dominance (v = 0.12 ÷ 0.95) the measured integrated probability (1.160 ± 0.040stat ± 0.075syst) · 10−4 is in agreement with the theoretical value of 1.185 · 10−4, obtained using the Petrukhin and Shestakov description of the bremsstrahlung process. The same result is about 3.6 standard deviations (defined as the quadratic sum of statistical and systematic errors) lower than the theoretical prediction of 1.472 · 10−4, obtained using Tsai’s description of bremsstrahlung.
Measured differential probability values DPROB/DNU for fractional energy loss. Only statistical errors are given.
Integrated probability (DELTA(PROB)) per radiation length.
This paper completes the detailed presentation of our PV experiment on the 6S1/2 - 7S1/2 transition in Cs. A detailed description of the data acquisition and processing is given. The results of two independent measurements made on ΔF = 0 and ΔF =1 hfs components agree, providing an important cross-check. After a complete reanalysis of systematics and calibration, the precision is slightly improved, leading to the weighted average Im Epv 1/β = - 1.52 ± 0.18 mV/cm. Later results from an independent group agree quite well. With the semi-empirical value β = (26.8 ± 0.8) a30, our result yields Epv1 = (- 0.79 ± 0.10) x 10-11 i |e|a0. Coupled with the atomic calculations, this implies that the weak nuclear charge of Cs is Qw = -68 ± 9. This value agrees with the standard electroweak theory and leads to a weak interaction angle sin2 θ W = 0.21 ± 0.04. The complementarity of these measurements with high energy experiments is illustrated.
Revision of the earlier experiment PL 117B, 358. (7s)2S1/2:F=4 --> (6s)2S1/2:F=4 transition.
Revision of the earlier experiment PL 134B, 463. (7s)2S1/2:F=3 --> (6s)2S1/2:F=4 transition.
Combined of the two above measurements following the philosophy: quadratic sum of the statistical and systematic uncertainties and weighting each result by the squared reciprocal of that uncertainty. (7s)2S1/2 --> (6s)2S1/2 transitions.
A simple, large-solid-angle apparatus, specially suited for the measurement of backward elastic scattering of medium-energy pions on protons and deuterons, is described. The method of analysis which reduces background and determines elastic events from a data sample of 185 MeV negative pions incident on a D 2 O target is discussed. Results for 141 MeV π + p and 185 MeV π − p backward cross-sections are also presented and compared with cross-sections calculated from known phase shifts.
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