Studies of the radiation hardness of lead tungstate crystals produced by the Bogoroditsk Techno-Chemical Plant in Russia and the Shanghai Institute of Ceramics in China have been carried out at IHEP, ...Protvino. The crystals were irradiated by a 40-GeV pion beam. After full recovery, the same crystals were irradiated using a \(^{137}Cs\) \(\gamma\)-ray source. The dose rate profiles along the crystal length were observed to be quite similar. We compare the effects of the two types of radiation on the crystals light output.
The talk continues the series of Single Spin Asymmetry (SSA) \(\pi^0\) inclusive measurements carried out at Protvino 70 GeV accelerator. The asymmetry in the polarized target fragmentation region ...grows up in absolute value with \(\xf\) decreasing and equals to \((-16 \pm 5)%\) at \(-0.4<\xf<-0.25\). The result of the current experiment is in agreement with the universal threshold in pion asymmetries.
The inclusive \(\pi^0\) asymmetries were measured in reactions \(p+p\uparrow \to \pi^0+X\) and \(\pi^-+p\uparrow \to \pi^0+X\) at 70 and 40 GeV/c respectively. The measurements were made at the ...central region (for the first reaction) and asymmetry is compatible with zero in the entire measured \(p_T\) region. For the second reaction the asymmetry is zero for small \(x_F\) region (\(-0.4<x_F<-0.1, 0.5<p_T(GeV/c) <1.5\)) and increases with growth of \(\mid x_F\mid\). Averaged over the interval \(-0.8<x_F<-0.4, 1<p_T(GeV/c)<2\) the asymmetry was \(-(13.8\pm 3.8)%\).
A highly stable monitoring system based on blue and red light emitting diodes coupled to a distribution network comprised of optical fibers has been developed for an electromagnetic calorimeter that ...uses lead tungstate crystals readout with photomultiplier tubes. We report of the system prototype design and on the results of laboratory tests. Stability better than 0.1% (r.m.s.) has been achieved during one week of prototype operation.
We employed two independent methods to study possible damage to the scintillation mechanism in lead tungstate crystals due to irradiation by a 34 GeV pion beam. First, 10 crystals were irradiated ...simultaneously over 30 hours by a narrow beam, so that only a small region of each crystal was affected. We studied the effect of the irradiation on the light output non-uniformity. If a localized degradation was observed, it would indicate damage to the scintillation mechanism. Secondly, we detected light output using two phototubes attached to sides of a crystal. Since these phototubes detect scintillation light only from a small localized region, the effect of transmission loss should be minimal. We did not see any statistically significant evidence for scintillation mechanism damage with either method. The effect is consistent with zero, and the upper limit is 0.5% at 95% C.L.
The energy dependence of the energy and position resolutions of the electromagnetic calorimeter prototype made of lead tungstate crystals produced in Bogoroditsk (Russia) and Shanghai (China) is ...presented. These measurementswere carried out at the Protvino accelerator using a 1 to 45 GeV electron beam. The crystals were coupled to photomultiplier tubes. The dependence of energy and position resolutions on different factors as well as the measured electromagnetic shower lateral profile are presented.
We report on the effects of radiation on the light output of lead tungstate crystals. The crystals were irradiated by pure, intense high energy electron and hadron beams as well as by a mixture of ...hadrons, neutrons and gammas. The crystals were manufactured in Bogoroditsk, Apatity (both Russia), and Shanghai (China). These studies were carried out at the 70-GeV proton accelerator in Protvino.
A beam line for electrons with energies in the range of 1 to 45 GeV, low contamination of hadrons and muons and high intensity up to 10^6 per accelerator spill at 27 GeV was setup at U70 accelerator ...in Protvino, Russia. A beam tagging system based on drift chambers with 160 micron resolution was able to measure relative electron beam momentum precisely. The resolution sigma_p p was 0.13% at 45 GeV where multiple scattering is negligible. This test beam setup provided the possibility to study properties of lead tungstate crystals (PbWO_4) for the BTeV experiment at Fermilab.
The analyzing power ital Asub ital N of proton-proton elastic scattering in the Coulomb-nuclear interference region has been measured using the 200-GeV/ital c Fermilab polarized proton beam. A ...theoretically predicted interference between the hadronic non-spin-flip amplitude and the electromagnetic spin-flip amplitude is shown for the first time to be present at high energies in the region of 1.5times10sup minus3 to 5.0times10sup minus2 (GeV/ital c)sup 2 four-momentum transfer squared, and our results are analyzed in connection with theoretical calculations. In addition, the role of possible contributions of the hadronic spin-flip amplitude is discussed.
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