103266766
Binding energy of (Lambda)He-7 and test of charge symmetry breaking in the Lambda N interaction potential
The binding energy of 7ΛHe has been obtained for the first time with reaction spectroscopy using the (e, e'K+) reaction at Jefferson Lab's Hall C. A comparison among the binding energies of the A = 7 T = l iso-triplet hypernuclei, 7ΛHe, 7ΛLi*and 7ΛBe, is made and possible charge symmetry breaking (CSB) in the ΛN potential is discussed. For 7ΛHe and 7ΛBe, the shifts in binding energies are opposite to those predicted by a recent cluster model calculation, which assumes that the unexplained part of the binding energy difference between 4ΛH and 4ΛHe, is due to the CSB of the ΛN potential. Further examination of CSB in light hypernuclear systems is required both experimentally and theoretically.
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.
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).
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.
123038966
Measurement of tensor polarization of deuterons from 3He->d+p breakup at momenta from 4.60 to 5.66 GeV/c
The tensor polarization p{sub 20} of deuterons emitted in the {sup 1}H(3{sup 3}He,d{leftrightarrow})X reaction at 0{sup o} in the laboratory system was measured at the Saturne National Laboratory in Saclay using the SPES-4 spectrometer with the HYPOM polarimeter located downstream from its focal plane. The momentum of the detected deuterons was kept fixed at 3.77 GeV/c, while the momentum of the {sup 3}He beam was varied from 4.60 to 5.66 GeV/c, thus providing a range of internal momenta k of the deuteron in {sup 3}He from 0 up to 0.4 GeV/c. The data obtained are compared with theoretical predictions.
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%.
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
115599731
Top Mass Measurement
117310029
Simulation of LiCAS Error Propagation
Linear Collider Alignment and Survey (LiCAS) R&D group is proposing a novel automated metrology instrument dedicated to align and monitor the mechanical stability of a future linear high energy e + e collider. LiCAS uses Laser Straightness Monitors (LSM) and Frequency Scanning Interferometry (FSI) [2, 3] for straightness and absolute distance measurements, respectively. This paper presents detailed simulations of a LiCAS system operating inside a Rapid Tunnel Reference Surveyor (RTRS train). With the proposed design it is feasible to achieve the required vertical accuracy of the order of O(200)µm over 600m tunnel sections meeting the specification for the TESLA collider [4]. 1 Principle of the LICAS-RTRS train operation In figure 1 the schematic view of the LiCAS train operating in the accelerator tunnel is presented. The train is composed of 6 cars, the distance between the centres of neighbouring cars is � 4.5m. Each car is equipped with 4 CCD cameras and two beam splitters (BS) constituting the straightness monitor. The straightness monitor measures the transverse translation (Tx,Ty) and transverse rotation (Rx,Ry) with respect to a z axis defined by the laser beam passing through all cars in a vacuum pipe. The laser beam is reflected back using the retro-reflector (RR) located in the last car, illuminating the upper CCD cameras of the straightness monitors. 6 FSI lines placed in the same vacuum pipe between each pair of cars are responsible for the distance measurement along the z axis (Tz). In addition a clinometer located on each car provides a measurement of rotation around the z axis (Rz). When the train stops in front of the wall markers it firstly measures the relative position and rotation of all cars with respect to the first car. This defines the local reference frame of the train in which the location of the wall mounted reference markers are measured next. This procedure is repeated for each train stop. Each marker is measured up to 6 times. Finally the coordinates of each marker, expressed in the local train frames are transformed to the frame of the first train (the global frame) by fitting them to each other under the constraint that wall markers have not moved during the entire measurement. 2 Opto-geometrical model of the LICAS-RTRS train In order to study the expected precision on the position reconstruction of the tunnel reference markers a simulation of the LiCAS survey train was performed. To describe the sensing parts of the train the Simulgeo [5] package was used which allows for modelling
16805647
A Detailed Monte Carlo simulation for the BELLE TOF system
We have developed a detailed Monte Carlo simulation program for the Belle time-of-flight (TOF) system. Based on GEANT simulation, it takes account of all physics processes in the TOF scintillation counters and readout electronics. The simulation reproduces very well the performance of the Belle TOF system, including the dE/dx response, the time walk effect, the time resolution, and the hit efficiency due to beam background. In this report, we will describe the Belle TOF simulation program in detail.