33219157
Comparison of Polarization Observables in Electron Scattering from the Proton and Deuteron
Recoil proton polarization observables were measured for both the p({rvec e},e{sup {prime}} {rvec p}) and d({rvec e},e{sup {prime}} {rvec p})n reactions at two values of Q{sup 2} using a newly commissioned proton focal plane polarimeter at the MIT-Bates Linear Accelerator Center. The hydrogen and deuterium spin-dependent observables D{sub scr(ll)} and D{sub scr(l)t} , the induced polarization P{sub n} , and the form factor ratio G{sup p}{sub E}/G{sup p}{sub M} were measured under identical kinematics. The deuterium and hydrogen results are in good agreement with each other and with the plane-wave impulse approximation (PWIA). {copyright} {ital 1998} {ital The American Physical Society}
118914530
Measurement of Analyzing Powers for Polarized Proton Scattering on CH2 Target at Proton Momentum Range from 1.75 to 5.3 GeV/c
We report a new measurement of analyzing powers for the reaction p + CH2 → one charged particle +X, at proton momenta of 1.75, 3.8, 4.5 and 5.3 GeV/c. These results extend the existing data basis, necessary for proton polarimetry at intermediate energy, and confirm the feasibility of an extended polarimeter based on this process. The experiment is performed at the accelerator complex of the JINR‐LHE (Dubna).
29593010
Pion absorption above the Delta (1232) resonance.
Two-proton and three-proton inclusive [pi][sup +] absorption cross sections were measured for incident pion energies from 250 to 500 MeV on targets of [sup 12]C, [sup 58]Ni, [sup 90]Zr, [sup 118]Sn, and [sup 208]Pb using a large solid angle bismuth germanate detector array. Pion absorption events leading to three or more protons in the final state were observed to become more significant with increasing incident pion energy and were dominant at 500 MeV. The total absorption cross sections were inferred from analyses of the data with uncertanties of approximately 25%.
119878792
Measurement of the ratio of the proton's electric to magnetic form factors by recoil polarization
The longitudinal and transverse polarizations of the outgoing proton were measured for the reaction {sup 1}H(e,e' p) at four-momentum transfer squared of 0.5 to 3.5 GeV{sup 2}. The ratio of the electric to magnetic form factors of the proton is proportional to the ratio of the transverse to longitudinal polarizations.
54739743
The aerogel threshold Cherenkov detector for the High Momentum Spectrometer in Hall C at Jefferson Lab
We describe a new aerogel threshold Cherenkov detector installed in the HMS spectrometer in Hall C at Jefferson Lab. The Hall C experimental program in 2003 required an improved particle identification system for better identification of p=K=p, which was achieved by installing an additional threshold Cherenkov counter. Two types of aerogel with n 1⁄4 1:030 and n 1⁄4 1:015 allow one to reach 10 3 proton and 10 2 kaon rejection in the 1–5GeV/c momentum range with pion detection efficiency better than 99% (97%). The detector response shows no significant position dependence due to a diffuse light collection technique. The diffusion box was equipped with 16 Photonis XP4572 photo multiplier tubes (PMTs). The mean number of photo-electrons in saturation was 16 and 8, respectively. This allows even for separation of slower particles slightly above threshold. r 2005 Elsevier B.V. All rights reserved. PACS: 29.40.Ka; 25.30.Rw
43065058
Pion absorption in light nuclei.
Cross sections have been measured for proton emission following ${\mathrm{\ensuremath{\pi}}}^{+}$ absorption on $^{6}\mathrm{Li}$, $^{7}\mathrm{Li}$, $^{9}\mathrm{Be}$, $^{10}\mathrm{B}$, $^{11}\mathrm{B}$, $^{12}\mathrm{C}$, and $^{13}\mathrm{C}$, for pion kinetic energies of 50, 100, 140, and 180 MeV using a large-solid-angle bismuth germanate detector array.
123029644
Observation of short-lived particles produced in high energy neutrino interactions
Abstract Examination of a sample of 89 high-energy, neutrino-induced dilepton events produced in the Fermilab 15 ft bubble chamber has resulted in the direct observation of the production and visible semi-leptonic decay of short-lived particles. One charged decay, two neutral decays, and one decay candidate of undetermined charge are found. Assuming these events and the remaining dilepton signal result from D meson decays, we obtain τ D + = 2.5 −1.5 +3.5 × 10 −13 s and τ D 0 = 3.5 −1.7 +3.5 × 10 −13 s, using a maximum likelihood analysis.
117932304
Tevatron bunch length studies at CDF
A luminous interaction region can be described by the distribution in (x, y, z) over which p{bar p} interactions are observed in a detector. The spatial size of this distribution can be written in terms of expressions that involve only combinations of the proton and anti-proton bunch sizes. Hence, it is not possible to determine the sizes of the proton and anti-proton bunches independently by fitting the distribution of (x, y, z) from the recorded events. If, in addition to the coordinates (x, y, z) at which p{bar p} interactions occur, the times at which the interactions took place are also measured, then it becomes possible to measure the lengths of the proton and anti-proton bunches separately. This sensitivity is due to a correlation between z and t that arises from the fact that the proton and anti-proton bunches travel in opposite directions. The derivation presented in section 2 quantifies this correlation, resulting in an expression for the probability density as a function of z and t for p{bar p} interactions. By fitting the distributions observed at CDF using this model, we measure the lengths of the proton and anti-proton bunches at times throughout several Tevatron stores. From this analysismore » the evolution of the bunch lengths can be studied. We attempt to correlate these with other measures of the bunch length obtained using different experimental techniques.« less
54531093
First Data from the Linear Collider Alignment and Survey Project (LiCAS)
The LiCAS project has developed a prototype robotic survey system for rapid and highly accurate surveying of long linear accelerator tunnel networks. It is aimed at the International Linear Collider (ILC). This Rapid Tunnel Reference Surveyor (RTRS) is an R&D instrument for evaluating the performance of the RTRS concept and its survey technology. The prototype has been commissioned in a test tunnel at DESY with initial calibrations and measurements ongoing. We will report recent results where they improve over previously reported work. This report was presented in the EPAC Conference under the reference TUPC118
54051753
New Measurements of Upsilon Spin Alignment at the Tevatron
We describe a new analysis of {Upsilon}(nS) {yields} {mu}{sup +}{mu}{sup -} decays collected in p{bar p} collisions with the CDF II detector at the Fermilab Tevatron. This analysis measures the angular distributions of the final state muons in the {Upsilon} rest frame, providing new information about {Upsilon} production polarization. We find the angular distributions to be nearly isotropic up to {Upsilon} p{sub T} of 40 GeV/c, consistent with previous measurements by CDF, but inconsistent with results obtained by the D0 experiment. The results are compared with recent NLO calculations based on color-singlet matrix elements and non-relativistic QCD with color-octet matrix elements.
204013563
KEKB beam collision stability at the picosecond timing and micron position resolution as observed with the Belle detector
Using the Belle detector we study the characteristics of beam collisions at the KEKB 3.5 GeV e+ on 8 GeV e− asymmetric energy collider. We investigate the collision timing tIP and its z-coordinate along the beam axis zIP as a function of the position of the colliding bunch in a beam train. The various tIP and zIP behaviors observed by Belle are attributed to beam loading effects in the radio frequency cavities that accelerate the beams with a beam abort gap. We report these results in detail and discuss the prospects for the SuperKEKB collider.