21 Matching Results

Search Results

Advanced search parameters have been applied.

STUDY OF THE RHIC BPM SMA CONNECTOR FAILURE PROBLEM

Description: About 730 BPMs are mounted on the RHIC CQS and Triplet super-conducting magnets. Semi-rigid coaxial cables are used to bring the electrical signal from the BPM feedthroughs to the outside flanges. at the ambient temperature. Every year around 10 cables will lose their signals during the operation. The connection usually failed at the warm end of the cable. The problems were either the solder joint failed or the center conductor retracted out of the SMA connector. Finite element analyses were performed to understand the failure mechanism of the solder joint. The results showed that (1) The SMA center conductor can separate from the mating connector due to the thermal retraction. (2) The maximum thermal stress at the warm end solder joint can exceed the material strength of the Pb37/Sn63 solder material and (3) The magnet ramping frequency (-10 Hz), during the machine startup, can possibly resonant the coaxial cable and damage the solder joints, especially when a fracture is initiated. Test results confirmed that by using the silver bearing solder material (a higher strength material) and by crimping the cable at the locations close to the SMA connector (to prevent the center conductor from retracting) can effectively resolve the connector failure problem.
Date: June 25, 2007
Creator: LIAW,C.; SIKORA, R. & SCHROEDER, R.
Partner: UNT Libraries Government Documents Department

Gravity and magnetic study of Yucca Wash, southwest Nevada

Description: Gravity and ground magnetic data were collected along five traverses across and one traverse along Yucca Wash in the southwest quadrant of the Nevada Test Site. Two additional ground magnetic profiles were collected approximately 100 m to either side of the longitudinal profile. These data do not indicate major vertical offsets greater than 100 m using a density contrast of 0.2 to 0.3 g/cm{sup 3} along the proposed Yucca Wash fault. A broad magnetic high coincides with the location of the hydrologic gradient. Density profiling, a technique used to determine the average density of small topographic features, suggests that the density of near-surface material in the vicinity of Yucca Wash is about 2.0 g/cm{sup 3}.
Date: December 31, 1993
Creator: Langenheim, V.E.; Ponce, D.A.; Oliver, H.W. & Sikora, R.F.
Partner: UNT Libraries Government Documents Department

Aeromagnetic surveys across Crater Flat and parts of Yucca Mountain, Nevada

Description: As part of a study to characterize a potential nuclear waste repository at Yucca Mountain, aeromagnetic surveys were conducted in April 1993 along the trace of a planned seismic profile across Crater Flat and parts of Yucca Mountain. This report includes a presentation and preliminary interpretation of the data. The profiles are at scales of 1:100,000. Also included are a gridded color contour map of the newly acquired data and a discussion of the likely applicability of very-low-frequency (VLF) electromagnetic surveys to Yucca Mountain investigations.
Date: December 31, 1995
Creator: Sikora, R.F.; Campbell, D.L. & Kucks, R.P.
Partner: UNT Libraries Government Documents Department

Major results of gravity and magnetic studies at Yucca Mountain, Nevada

Description: About 4000 gravity stations have been obtained at Yucca Mountain and vicinity since the beginning of radioactive-waste studies there in 1978. These data have been integrated with data from about 29,000 stations previously obtained in the surrounding region to produce a series of Bouguer and isostatic-residual-gravity maps of the Nevada Test Site and southeastern Nevada. Yucca Mountain is characterized by a WNW-dipping gravity gradient whereby residual values of {minus}10 mGal along the east edge of Yucca Mountain decrease to about {minus}38 mGal over Crater Flat. Using these gravity data, two-dimensional modeling predicted the depth to pre-Cenozoic rocks near the proposed repository to be about 1220 {plus_minus} 150 m, an estimate that was subsequently confirmed by drilling to be 1244 m. Three-dimensional modeling of the gravity low over Crater Flat indicates the thickness of Cenozoic volcanic rocks and alluvial cover to be about 3000 m. Considerable aeromagnetic coverage of southwestern Nevada was obtained in 1978--1979 to help characterize Yucca Mountain and vicinity. One significant result is the discovery of a series of circular magnetic anomalies in Crater Flat and the northern Amargosa Desert that suggest the presence of buried volcanic centers there. Elongate magnetic highs and associated lows over Yucca Mountain correlate with mapped faults, some of which are only partially exposed. Thus, the data provide inforamtion on the extent and continuity of these faults. 31 refs., 3 figs.
Date: May 1, 1991
Creator: Oliver, H.W.; Ponce, D.A. & Sikora, R.F.
Partner: UNT Libraries Government Documents Department

Preliminary studies on a magneto-optical procedure for aligning RHIC magnets

Description: Colloid dispersions of magnetite were used at SLAC and KEK to locate multipole magnet centers. We study the possible adaption of this method, to align RHIC magnets. A procedure for locating magnetic centers with respect to external fiducial markers, using electronic coordinate determination and digital TV image processing is described.
Date: June 1, 1993
Creator: Goldman, M. A.; Sikora, R. E. & Shea, T. J.
Partner: UNT Libraries Government Documents Department

THE Low-level Radio Frequency System for the superconducting cavities of National Synchrotron Light Source II

Description: A digital low-level radio frequency (LLRF) field controller has been developed for the storage ring of The National Synchrotron Light Source-II (NSLS-II). The primary performance goal for the LLRF is to support the required RF operation of the superconducting cavities with a beam current of 500mA and a 0.14 degree or better RF phase stability. The digital field controller is FPGA-based, in a standard format 19-inch/I-U chassis. It has an option of high-level control support with MATLAB running on a local host computer through a USB2.0 port. The field controller has been field tested with the high-power superconducting RF (SRF) at Canadian light Source, and successfully stored a high beam current of 250 mA. The test results show that required specifications for the cavity RF field stability are met. This digital field controller is also currently being used as a development platform for other functional modules in the NSLS-II RF systems.
Date: March 28, 2011
Creator: Ma, H.; Rose, J.; Holub, B.; Cupolo, J.; Oliva, J.; Sikora, R. et al.
Partner: UNT Libraries Government Documents Department

Gravity and magnetic data of Midway Valley, southwest Nevada

Description: Detailed gravity and ground magnetic data collected along five traverses across Midway Valley on the eastern flank of Yucca Mountain in southwest Nevada are described. These data were collected as part of an effort to evaluate faulting in the vicinity of proposed surface facilities for a potential nuclear waste repository at Yucca Mountain. Geophysical data show that Midway Valley is bounded by large gravity and magnetic anomalies associated with the Bow Ridge and Paintbrush Canyon faults, on the west side of Exile Hill and on the west flank of Fran Ridge, respectively. In addition, Midway Valley itself is characterized by a number of small-amplitude anomalies that probably reflect small-scale faulting beneath Midway Valley.
Date: December 31, 1993
Creator: Ponce, D. A.; Langenheim, V. E. & Sikora, R. F.
Partner: UNT Libraries Government Documents Department

Gravity and magnetic data across the Ghost Dance Fault in WT-2 Wash, Yucca Mountain, Nevada

Description: Detailed gravity and ground magnetic data were obtained in September 1993 along a 4,650 ft-long profile across the Ghost Dance Fault system in WT-2 Wash. Gravity stations were established every 150 feet along the profile. Total-field magnetic measurements made initially every 50 ft along the profile, then remade every 20 ft through the fault zone. These new data are part of a geologic and geophysical study of the Ghost Dance Fault (GDF) which includes detailed geologic mapping, seismic reflection, and some drilling including geologic and geophysical logging. The Ghost Dance Fault is the only through-going fault that has been identified within the potential repository for high-level radioactive waste at Yucca Mountain, Nevada. Preliminary gravity results show a distinct decrease of 0.1 to 0.2 mGal over a 600-ft-wide zone to the east of and including the mapped fault. The gravity decrease probably marks a zone of brecciation. Another fault-offset located about 2,000 ft to the east of the GDF was detected by seismic reflection data and is also marked by a distinct gravity low. The ground magnetic data show a 200-ft-wide magnetic low of about 400 nT centered about 100 ft east of the Ghost Dance Fault. The magnetic low probably marks a zone of brecciation within the normally polarized Topopah Spring Tuff, the top of which is about 170 ft below the surface, and which is known from drilling to extend to a depth of about 1,700 ft. Three-component magnetometer logging in drill hole WT-2 located about 2,700 ft east of the Ghost Dance Fault shows that the Topopah Spring Tuff is strongly polarized magnetically in this area, so that fault brecciation of a vertical zone within the Tuff could provide an average negative magnetic contrast of the 4 Am{sup {minus}1} needed to produce the 400 nT low observed at ...
Date: December 31, 1994
Creator: Oliver, H.W. & Sikora, R.F.
Partner: UNT Libraries Government Documents Department

Status of aeromagnetic survey coverage of Yucca Mountain and vicinity to a radius of about 140 kilometers, southwestern Nevada and southeastern California, 1992

Description: Fifty aeromagnetic surveys in the southwestern part of Nevada and the southeastern part of California have been evaluated to assess the quality and coverage of aeromagnetic data within 140 kilometers (km) of a potential nuclear waste repository at Yucca Mountain, Nevada. The compilation shows that all the study area is covered by aeromagnetic surveys, but in some areas, particularly in the Death Valley region, new surveys flown with closer flight line spacing and lower elevations than the existing coverage are needed. In addition, the California part of the study area needs to be analytically continued downward to 305 meters (m) above ground level to provide a consistent data set for interpretation of subsurface geologic structures.
Date: December 31, 1993
Creator: Sikora, R. F.; Ponce, D. A. & Oliver, H. W.
Partner: UNT Libraries Government Documents Department

Processing and evaluation of the AGS Booster ultra-high vaccum system

Description: The AGS Booster is a synchrotron for the acceleration of both protons and heavy ions. To minimize the beam loss due to charge exchange of the partially stripped, low {Beta} very heavy ions with the residual gas molecules, pressure of low 10{sup {minus}11} Torr is required for the 200 m booster ring. To achieve this ultra high vacuum, chemical cleaning, vacuum furnace degassing and insitu bake were employed for all chambers and beam components. Using these procedures, vacuums of low 10{sup {minus}11} Torr have been routinely achieved during the testing of individual half cells and beam components, and during the commissioning of the vacuum sectors. In this paper, the design and layout of chambers, flanges and bakeout hardware is briefly described. The vacuum processing of different components and the results of bakeout and evaluation are summarized. The experience gained during the construction and commissioning of this ultra-high vacuum system is also given. 3 refs., 3 figs., 1 tab.
Date: January 1, 1991
Creator: Hseuh, H.C.; Mapes, M.; Schnitzenbaumer, P.; Shen, B.; Sikora, R. & Stattel, P.
Partner: UNT Libraries Government Documents Department

ELECTROMAGNETIC FIELD MEASUREMENT OF FUNDAMENTAL AND HIGHER-ORDER MODES FOR 7-CELL CAVITY OF PETRA-II

Description: The booster synchrotron for NSLS-II will include a 7-cell PETRA cavity, which was manufactured for the PETRA-II project at DESY. The cavity fundamental frequency operates at 500 MHz. In order to verify the impedances of the fundamental and higher-order modes (HOM), which were calculated by computer code, we measured the magnitude of the electromagnetic field of the fundamental acceleration mode and HOM using the bead-pull method. To keep the cavity body temperature constant, we used a chiller system to supply cooling water at 20 degrees C. The bead-pull measurement was automated with a computer. We encountered some issues during the measurement process due to the difficulty in measuring the electromagnetic field magnitude in a multi-cell cavity. We describe the method and apparatus for the field measurement, and the obtained results.
Date: March 28, 2011
Creator: Kawashima, Y.; Blednykh, A.; Cupolo, J.; Davidsaver, M.; Holub, B.; Ma, H. et al.
Partner: UNT Libraries Government Documents Department

LASER PROFILE MEASUREMENTS OF AN H BEAM.

Description: A non-intercepting beam profile monitor for H{sup {minus}} beams is being developed at Brookhaven National Lab. An H{sup {minus}} ion has a first ionization potential of 0.75eV. Electrons can be removed from an H{sup {minus}} beam by passing light from a near-infrared laser through it. Experiments have been performed on the BNL linac to measure the transverse profile of a 750keV beam by using a Nd:YAG laser to photoneutralize narrow slices of the beam. The laser beam is scanned across the ion beam neutralizing the portion of the beam struck by the laser. The electrons are removed from the ion beam and the beam current notch is measured.
Date: May 12, 2001
Creator: CONNOLLY,R.; CAMERON,P.; CUPOLO,J.; GRAU,M.; KESSELMAN,M.; LIAW,C.J. et al.
Partner: UNT Libraries Government Documents Department

LASER PROFILE MEASUREMENTS OF AN H BEAM.

Description: A non-intercepting beam profile monitor for He beams is being developed at Brookhaven National Lab. An H{sup {minus}} ion has a first ionization potential of 0.75eV. Electrons can be removed from an H{sup {minus}} beam by passing light from a near-infrared laser through it. Experiments have been performed on the BNL linac to measure the transverse profile of a 750keV beam by using a Nd:YAG laser to photoneutralize narrow slices of the beam. The laser beam is scanned across the ion beam neutralizing the portion of the beam struck by the laser. The electrons are removed from the ion beam and the beam current notch is measured.
Date: June 18, 2001
Creator: CONNOLLY,R.; CAMERON,P.; CUPOLO,J.; GRAU,M.; KESSELMAN,M.; LIAW,C.J. et al.
Partner: UNT Libraries Government Documents Department

SCHOTTKY MEASUREMENTS DURING RHIC 2000.

Description: The 2GHz Schottky system was a powerful diagnostic during RHIC 2000 commissioning. A continuous monitor without beam excitation, it provided betatron tune, chromaticity, momentum spread relative emittance, and synchrotron tune. It was particularly useful during transition studies. In addition, a BPM was resonated at 230MHz for Schottky measurements.
Date: June 18, 2001
Creator: CAMERON,P.; CUPOLO,J.; DEGEN,C.; HAMMONS,L.; KESSELMAN,M.; LEE,R. et al.
Partner: UNT Libraries Government Documents Department

LASER BEAM PROFILE MONITOR DEVELOPMENT AT BNL FOR SNS.

Description: A beam profile monitor for H-beams based on laser photoneutralization is being developed at Brookhaven National Laboratory (BNL) for use on the Spallation Neutron Source (SNS) [l]. An H ion has a first ionization potential of 0.75eV and can be neutralized by light from a Nd:YAG laser (h=1064nm). To measure beam profiles, a narrow laser beam is passed through the ion beam neutralizing a portion of the H-beam struck by the laser. The laser trajectory is stepped across the ion beam. At each laser position, the reduction of the beam current caused by the laser is measured. A proof-of-principle experiment was done earlier at 750keV. This paper reports on measurements made on 200MeV beam at BNL and with a compact scanner prototype at Lawrence Berkeley National Lab on beam from the SNS RFQ.
Date: May 6, 2002
Creator: CONNOLLY,R.; CAMERON,P.; CUPOLO,J.; GASSNER,D.; GRAU,M.; KESSELMAN,M. et al.
Partner: UNT Libraries Government Documents Department

BPM SYSTEM FOR THE SNS RING AND TRANSFER LINES.

Description: The Spallation Neutron Source Ring accumulates about 1060 pulses of 38mA peak current IGeV H-minus particles from the Linac thru the HEBT line, then delivers this accumulated beam in a single pulse to the mercury target via the RTBT line. Bunching frequency of beam in the HEBT line is 402.5MHz, and about 1MHz in the Ring and RTBT. Position monitor electrodes in HEBT are of the shorted stripline type, with apertures of 12cm except in the dispersive bend, where the aperture is 21cm. Ring and RTBT electrodes are open striplines, with apertures of 21, 26, 30, and 36cm. All pickups are dual plane. The electronics will be PC-based with the Analog/Digital Front End passing data and receiving control and timing thru a custom PC1 interface developed by LANL[l]. LabVIEW will be used to direct the acquisition, process the data, and transfer results via Ethernet to the EPICS control system. To handle the dynamic range required with well over 60dB variation in signal size, the Ring and RTBT electronics will employ a fast gain switching technique that will take advantage of the 300ns tail-to-head gap to provide position measurement during the entire accumulation cycle. Beam-based alignment will be utilized as part of the system calibration.
Date: May 6, 2002
Creator: DAWSON,W.C.; CAMERON,P.; CERNIGLIA,P.; CUPOLO,J.; DEGEN,C.; DELLAPENNA,A. et al.
Partner: UNT Libraries Government Documents Department

RHIC BPM SYSTEM PERFORMANCE, UPGRADES, AND TOOLS.

Description: During the RHIC 2001-2 run, the beam position monitor (BPM) system provided independent average orbit and turn-by-turn (TBT) position measurements at 162 locations in each measurement plane and RHIC ring. TBT acquisition was successfully upgraded from 128 turns to 1024 turns per trigger, including injection. Closed orbits were acquired and automatically archived every two seconds through each acceleration ramp for orbit analysis and feed-forward orbit correction. This paper presents the overall system performance during this run, including precision, reproducibility, radiation damage, and analysis tools. We also summarize future plans, including million-turn TBT acquisition for nonlinear dynamics studies.
Date: June 2, 2002
Creator: SATOGATA,T.; CAMERON,P.; CERNIGLIA,P.; CUPOLO,J.; DAWSON,C.; DEGEN,C. et al.
Partner: UNT Libraries Government Documents Department

LASER BEAM PROFILE MONITOR DEVELOPMENT AT BNL FOR SNS.

Description: A beam profile monitor for H{sup -} beams using laser photoneutralization is being developed at Brookhaven National Laboratory [1] for use on the Spallation Neutron Source (SNS) [2]. An H{sup -} ion has a first ionization potential of 0.75eV and can be neutralized by light from a Nd:YAG laser ({lambda}=1064nm). To measure beam profiles, a narrow laser beam is passed through the ion beam neutralizing a portion of the H{sup -} beam struck by the laser, and the perturbation of the beam current caused by the laser is measured. The laser trajectory is stepped across the ion beam generating a transverse profile. Proof-of-principle experiments were done at 750keV and 200MeV. Also a compact scanner prototype was used at Lawrence Berkeley National Laboratory (LBNL) [3] during commissioning of the SNS RFQ.
Date: August 19, 2002
Creator: CONNOLLY,R.; CAMERON,P.; CUPOLO,J.; DAWSON,C.; DEGEN,C.; DELLA PENNA,A. et al.
Partner: UNT Libraries Government Documents Department

TUNE FEEDBACK AT RHIC

Description: Preliminary phase-locked loop betatron tune measurement results were obtained during RHIC 2000 with a resonant Beam Position Monitor. These results suggested the possibility of incorporating PLL tune measurement into a tune feedback system for RHIC 2001. Tune feedback is useful in a superconducting accelerator, where the machine cycle time is long and inefficient acceleration due to resonance crossing is not comfortably tolerated. This is particularly true with the higher beam intensities planned for RHIC 2001. We present descriptions of a PLL tune measurement system implemented in the DSP/FPGA environment of a RHIC BPM electronics module and the feedback system into which the measurement is incorporated to regulate tune. In addition, we present results from the commissioning of this system during RHIC 2001.
Date: June 18, 2001
Creator: Cameron, P.; Cerniglia, P.; Connoly, R.; Cupolo, J.; Dawson, W. C.; Degen, C. et al.
Partner: UNT Libraries Government Documents Department