42202614
Status of the NSRL Storage Ring UHV System after Project-II
The NSRL project-II has been finished in December 2004. The UHV system of storage ring has undergone improvement and now provide long beam lifetime and stable operations, the average pressure of ring is better than 2×10-8 Pascal without beam and 1×10-7 Pascal with beam, The typical beam lifetime is 12 hours at 300 mA and 800 MeV without wiggler and 8 hours at 300 mA and 800 MeV with wiggler on. The improvements and status of NSRL storage ring are described in this paper.
32668015
A Method to Calibrate Beam Position Monitor at HLS 200 MeV Linac
In order to improve injection efficiency of HLS 200Mev LINAC, we redesign a new strip line beam position monitor system, which is consisted of a strip line structure and a signal processing system. We decide on an online calibration method based on beam to find out the geometry centre displacement and relative gain offset. Before the BPM testing bench has been prepared, we make a simulation based on the model accounted for all factors influencing signal amplitudes and get the calibrating results. At last, we analyze the nonlinearity effect on the calibration results.
59428259
The upgrade of HLS linac control system
The linac control system of Hefei Light Source (HLS) was initially build in late 1980's, and a concerted effort has been put forth to upgrade it to a new, distributed one based on EPICS. Industrial PC based hardware is widely used as not only IOC but also front-end controller. Besides industrial PC, PLC and single-chip microcomputer are also used as front-end controllers in some subsystems. The software for industrial PC based front-end controller is developed based on vxWorks real-time operating system. The software for PLC and single-chip microcomputer are written with ladder software package and assemble language respectively. PC with Linux operating system and SUN workstation with Solaris operating system are used as operator interfaces. High level control is made up of some EPICS tools and Tcl/Tk scripts.
56077124
A closed orbit measurement with the NSRL BPM system
The beam position monitor system (BPM) of NSRL electron storage ring have a resolution of 10 microns with an accuracy of 50 microns, which is adequate fix beam position measurement and the closed orbit correction. The paper describes both of the BPM system and the closed orbit measurement.
19699493
Optical-fiber notch filter for storage ring transverse feedback system
An optical-fiber two-tap FIR (Notch) filter has been developed for storage ring transverse feedback system of Hefei light source. The optical notch filter has advantages of low loss, which is not related to the size of the storage ring, high-frequency response, and compact in size. Measurements have been done with storage ring beam signals. The paper presents the principle and the experimental results.
119075666
Beam test of BTeV pixel detectors
Abstract The silicon pixel vertex detector is one of the key elements of the BTeV spectrometer. Detector prototypes were tested in a beam at Fermilab. We report here on the measured spatial resolution as a function of the incident angles for different sensor-readout electronics combinations. We compare the results with predictions from our Monte Carlo simulation.
5695154
Precision measurements of the timelike electromagnetic form factors of pion, kaon, and proton.
Using 20.7 pb(-1) of e(+)e(-) annihilation data taken at sq.rt(r) = 3.671 GeV with the CLEO-c detector, precision measurements of the electromagnetic form factors of the charged pion, charged kaon, and proton have been made for timelike momentum transfer of |Q(2)| = 13.48 GeV(2) by the reaction e(+)e(-) --> h(+)h(-). The measurements are the first ever with identified pions and kaons of |Q(2)| > 4 GeV(2), with the results F(13.48 GeV(2)) = 0.075 +/- 0.008(stat) +/- 0.005(syst) and F(K)(13.48 GeV(2)) = 0.063 +/- 0.004(stat) +/- 0.001(syst). The result for the proton, assuming G(p)(E) = G(p)(M), is G(p)(M)(13.48 GeV(2)) = 0.014 +/- 0.002(stat) +/- 0.001(syst), which is in agreement with earlier results.
122200845
Search for same-sign top-quark pair production at $ \sqrt {s} = 7 $ TeV and limits on flavour changing neutral currents in the top sector
An inclusive search for same-sign top-quark pair production in pp collisions at $ \sqrt {s} = 7 $ TeV is performed using a data sample recorded with the CMS detector in 2010, corresponding to an integrated luminosity of 35 pb−1. This analysis is motivated by recent studies of $ \text{p}\bar{\text{p}} \to \text{t}\bar{\text{t}} $ reporting mass-dependent forward-backward asymmetries larger than expected from the standard model. These asymmetries could be due to Flavor Changing Neutral Currents (FCNC) in the top sector induced by t-channel exchange of a massive neutral vector boson (Z′). Models with such a Z′ also predict enhancement of same-sign top-pair production in pp or $ \text{p}\bar{\text{p}} $ collisions. Limits are set as a function of the Z′ mass and its couplings to u and t quarks. These limits disfavour the FCNC interpretation of the Tevatron results.