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Timing Jitter Characterization at the NSLS SDL
Two novel timing jitter measurement techniques with a 100 fs resolution are presented in this paper. The first technique based on the Schottky effect, is used to measure the timing jitter between the photoinjector drive laser and the RF system; and it was employed to characterize the environment effects on the timing jitter. The I/Q beam monitor based on a stripline beam position monitor (BPM) is used to characterize the electron beam arrival time jitter.
Date:
May 4, 2009
Creator:
Qian,H.; Hidaka, Y.; Murphy, J. B.; Podobedov, B.; Seletskiy, Shen, Y.; Yang, X. et al.
Object Type:
Article
System:
The UNT Digital Library
Linear Algebraic Method for Non-Linear Map Analysis
We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a matrix analysis method from linear algebra. Choosing the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of Jordan decomposition which is widely used in conventional linear algebra.
Date:
May 4, 2009
Creator:
Yu,L. & Nash, B.
Object Type:
Article
System:
The UNT Digital Library
Microwave Instability Simulations for NSLS-II
Potential-well distortion and the microwave instability in the NSLS-II storage ring are investigated. The longitudinal wakepotential is calculated as a sum of the contributions due to vacuum chamber components distributed around the ring. An approximation to the wakepotential for a 0.05-mm charge distribution length, much shorter than the 4.5-mm length of the unperturbed circulating bunch, is used as a pseudo-Green's function for beam dynamics simulations. Comparison of particle tracking simulations using the TRANFT code with the Haissinski solution shows good agreement below the instability threshold current. Above threshold two regimes are observed: (1) energy spread and bunch length are time-dependent (saw tooth behavior); (2) both are time-independent.
Date:
May 4, 2009
Creator:
Blednykh,A.; Krinsky, S.; Nash, B. & Yu, L.
Object Type:
Article
System:
The UNT Digital Library
Command Line Interface to Tracy Library
We describe a set of tools that interface to the Tracy particle tracking library. The state of the machine including misalignments, multipole errors and corrector settings is captured in a 'flat' file, or 'machine' file. There are three types of tools designed around this flat file: (1) flat file creation tools. (2) flat file manipulation tools. (3) tracking tools. We describe the status of these tools, and give some examples of how they have been used in the design process for NSLS-II.
Date:
May 4, 2009
Creator:
Nash,B.
Object Type:
Article
System:
The UNT Digital Library
Experimental Studies of Light Emission Phenomena in Superconducting RF Cavitites
Experimental studies of light emission phenomena in superconducting RF cavities, which we categorize under the general heading of cavity lights, are described. The cavity lights data, which were obtained using a small CCD video camera, were collected in a series of nine experimental runs ranging from {approx} 1/2 to {approx} 2 h in duration. The video data were recorded on a standard VHS tape. As the runs progressed, additional instrumentation was added. For the last three runs a LabVIEW controlled data acquisition system was included. These runs furnish evidence for several, possibly related, light emission phenomena. The most intriguing of these is what appear to be small luminous objects {le} 1.5 mm in size, freely moving about in the vacuum space, generally without wall contact, as verified by reflections of the tracks in the cavity walls. In addition, on a number of occasions, these objects were observed to bounce off of the cavity walls. The wall-bounce aspect of most of these events was clearly confirmed by pre-bounce and post-bounce reflections concurrent with the tracks. In one of the later runs, a mode of behavior was observed that was qualitatively different from anything observed in the earlier runs. Perhaps the most …
Date:
August 4, 2009
Creator:
Anthony, P. L.; Delayen, J. R.; Fryberger, D.; Goree, W. S.; Mammosser, J.; Szalata, Z. M. et al.
Object Type:
Article
System:
The UNT Digital Library
Defining a Possible Low LET Bystander Effect
Current radiation protection guidelines assume a linear response to ionizing radiations down through doses where epidemiological studies provide very limited to no information as to the propriety of such assumptions. The bystander response is a non-targeted effect which might impact such guidelines. These studies while clearly affirming a bystander response for high LET radiations, do not provide such affirmation for environmentally relevant low dose, low LET radiations. Caution and further study are necessary before making judgements that could impact on current standards.
Date:
May 4, 2009
Creator:
Geard, Charles R.
Object Type:
Report
System:
The UNT Digital Library
3D Simulations of Secondary Electron Generation and Transport in a Diamond Electron Beam Amplifier
The Relativistic Heavy Ion Collider (RHIC) contributes fundamental advances to nuclear physics by colliding a wide range of ions. A novel electron cooling section, which is a key component of the proposed luminosity upgrade for RHIC, requires the acceleration of high-charge electron bunches with low emittance and energy spread. A promising candidate for the electron source is the recently developed concept of a high quantum efficiency photoinjector with a diamond amplifier. To assist in the development of such an electron source, we have implemented algorithms within the VORPAL particle-in-cell framework for modeling secondary electron and hole generation, and for charge transport in diamond. The algorithms include elastic, phonon, and impurity scattering processes over a wide range of charge carrier energies. Results from simulations using the implemented capabilities will be presented and discussed.
Date:
May 4, 2009
Creator:
Busby, R.; Rao, T.; Dimitrov, D. A.; Cary, J. R.; Ben-Zvi, Ilan; Chang, X. et al.
Object Type:
Article
System:
The UNT Digital Library
Design Studies for a VUV--Soft X-ray Free-Electron Laser Array
Several recent reports have identified the scientific requirements for a future soft X-ray light source [1, 2, 3, 4, 5], and a high-repetition-rate free-electron laser (FEL) facility responsive to them is being studied at Lawrence Berkeley National Laboratory (LBNL) [6]. The facility is based on a continuous-wave (CW) superconducting linear accelerator with beam supplied by a high-brightness, high-repetition-rate photocathode electron gun operating in CW mode, and on an array of FELs to which the accelerated beam is distributed, each operating at high repetition rate and with even pulse spacing. Dependent on the experimental requirements, the individualFELs may be configured for either self-amplified spontaneous emission (SASE), seeded highgain harmonic generation (HGHG), echo-enabled harmonic generation (EEHG), or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format ranging from sub-femtoseconds to hundreds of femtoseconds. This new light source would serve a broad community of scientists in many areas of research, similar to existing utilization of storage ring based light sources. To reduce technical risks and constructioncosts, accelerator research, development, and design studies at LBNL target the most critical components and systems of the facility. We are developing a high-repetition-rate low-emittance electron gun, high quantum …
Date:
August 4, 2009
Creator:
Corlett, J.; Baptiste, K.; Byrd, J.M.; Denes, P.; Falcone, R.; Kirz, J. et al.
Object Type:
Article
System:
The UNT Digital Library
Longitudinal space charge effects near transition
Experimental and numerical studies of the longitudinal beam dynamics in the Small Isochronous Ring (SIR) at Michigan State University revealed a fast, space-charge driven instability that did not fit the model of the negative mass instability. This paper proposes a simple analytical model explaining these results. Also, the paper compares the model to result s of experimental and numerical studies of the longitudinal beam dynamics in SIR.
Date:
May 4, 2009
Creator:
Pozdeyev, E.; Rodriguez, J. A.; Marti, F. & York, R.C.
Object Type:
Article
System:
The UNT Digital Library
Design and Development of Selective Extractants for An/Ln Separations
This study has succeeded in further developing phosphinoylmethyl pyridine compounds as selective recognition and separations agents for trivalent lanthanide and actinide ions present in nuclear materials. The parameters for efficient separations have been further elucidated and factors important to further development have been identified. Further development will lead to optimal extractant design for effective actinide ion partitioning under process practical conditions. The primary objective of the project involved the design, synthesis, and characterization of the extraction performance of 2,6-bis(phosphinomethyl)pyridine N,P,P{prime}-trioxides (NOPOPO) as potential reagents for the separation of Am, Cm, and fission product lanthanides from other transuranics and fission products and for acting as a separations 'platform' for the mutual separation of Am/Cm from the lanthanides. The secondary but critical objective of the project focused on the characterization of aqueous acid and radiation stability of NOPOPO ligands. Further, the project served as a interdisciplinary training vehicle for new, young investigators in actinide separations chemistry.
Date:
December 4, 2009
Creator:
Paine, Robert T.
Object Type:
Report
System:
The UNT Digital Library
2007 Oak Ridge National Laboratory Annual Illness and Injury Surveillance Report
The U.S. Department of Energy’s (DOE) commitment to assuring the health and safety of its workers includes the conduct of epidemiologic surveillance activities that provide an early warning system for health problems among workers. The Illness and Injury Surveillance Program monitors illnesses and health conditions that result in an absence of workdays, occupational injuries and illnesses, and disabilities and deaths among current workers.
Date:
March 4, 2009
Creator:
United States. Department of Energy. Office of Health, Safety, and Security.
Object Type:
Report
System:
The UNT Digital Library
Ion bombardment in RF photoguns
A linac-ring eRHIC design requires a high-intensity CW source of polarized electrons. An SRF gun is viable option that can deliver the required beam. Numerical simulations presented elsewhere have shown that ion bombardment can occur in an RF gun, possibly limiting lifetime of a NEA GaAs cathode. In this paper, we analytically solve the equations of motion of ions in an RF gun using the ponderomotive potential of the Rf field. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper discusses possible mitigation techniques that can reduce the rate of ion bombardment.
Date:
May 4, 2009
Creator:
Pozdeyev, E.; Kayran, D. & Litvinenko, V. N.
Object Type:
Article
System:
The UNT Digital Library
Minimizing emittance growth during H- injection in the AGS booster
As part of the efforts to increase polarization and luminosity in RHIC during polarized proton operations we have modified the injection optics and stripping foil geometry in the AGS Booster in order to reduce the emittance growth during H{sup -} injection. In this paper we describe the modifications, the injection process, and present results from beam experiments.
Date:
May 4, 2009
Creator:
Brown, K. A.; Ahrens, L.; Gardner, C.; Gassner, D.; Raparia, D.; Steski, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Alternative Designs for the NSLS-II Injection Straight Section
Brookhaven National Laboratory (BNL) is developing a state-of-the-art 3 GeV synchrotron light source, the NSLS-II [1]. The 9.3 meter-long injection straight section of its storage ring now fits a conventional injection set-up consisting of four kickers producing a closed bump, together with a DC septum and a pulsed septum. In this paper, we analyze an alternative option based on injection via a pulsed sextupole magnet. We discuss the dynamics of the injected and stored beams and, subsequently, the magnet's specifications and tolerances. We conclude by summarized the advantages and drawbacks of each injection scheme.
Date:
May 4, 2009
Creator:
Shaftan,T.; Heese, R.; Weihreter, E.; Willeke, F.; Rehak, M.; Meier, R. et al.
Object Type:
Article
System:
The UNT Digital Library
Stochastic cooling in RHIC
After the success of longitudinal stochastic cooling of bunched heavy ion beam in RHIC, transverse stochastic cooling in the vertical plane of Yellow ring was installed and is being commissioned with proton beam. This report presents the status of the effort and gives an estimate, based on simulation, of the RHIC luminosity with stochastic cooling in all planes.
Date:
May 4, 2009
Creator:
Brennan,J. M.; Blaskiewicz, M. M. & Severino, F.
Object Type:
Article
System:
The UNT Digital Library
Impact of High-Order Multipole Errors in the NSLS-II Quadrupoles and Sectupoles on Dynamic and Momentum Aperture
Successful operation of NSLS-II requires sufficient dynamic aperture for injection, as well as momentum aperture for Touschek lifetime. We explore the dependence of momentum and dynamic aperture on higher-order multipole field errors in the quadrupoles and sextupoles. We add random and systematic multipole errors to the quadrupoles and sextupoles and compute the effect on dynamic aperture. We find that the strongest effect is at negative momentum, due to larger closed orbit excursions. Adding all the errors based on the NSLS-II specifications, we find adequate dynamic and momentum aperture.
Date:
May 4, 2009
Creator:
Nash,B. & Guo, W.
Object Type:
Article
System:
The UNT Digital Library
Results of LEBT/MEBT reconfiguration at BNL 200 MeV LINAC
The low energy (35 keV) and medium energy (750 keV) transport lines for both polarized and unpolarized H{sup -} have been reconfigured to reduce the beam emittance and beam losses out of the 200 MeV Linac. The medium energy line in the original layout was 7 m long, and had ten quadrupoles, two beam choppers, and three bunchers. The bunchers were necessary to keep the beam bunched at the entrance of the Linac. About 35% beam loss occurred, and the emittance growth was several fold. In the new layout, the 750 keV line is only 0.7 m long, with three quads and one buncher. We will present the experimental result of the upgrade.
Date:
May 4, 2009
Creator:
Raparia, D.; Alessi, J.; Briscoe, B.; Fite, J.; Gould, O.; Kponou, A. et al.
Object Type:
Article
System:
The UNT Digital Library
Aluminum Solubility and Its Effect on Sodium Management
This report addresses the aluminum solubility and its effect on sodium management.
Date:
June 4, 2009
Creator:
Herting, D. L.
Object Type:
Article
System:
The UNT Digital Library
Summary of operations and performance of the Murdock site restoration project in 2008.
This document summarizes the performance of the groundwater and surface water restoration systems installed by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) at the former CCC/USDA grain storage facility in Murdock, Nebraska, during the third full year of system operation, from January 1 through December 31, 2008. Performance in June 2005 through December 2007 was reported previously (Argonne 2007, 2008). In the Murdock project, several innovative technologies are being used to remove carbon tetrachloride contamination from a shallow aquifer underlying the town, as well as from water naturally discharged to the surface at the headwaters of a small creek (a tributary to Pawnee Creek) north of the town (Figure 1.1). The restoration activities at Murdock are being conducted by the CCC/USDA as a non-time-critical removal action under the regulatory authority and supervision of the U.S. Environmental Protection Agency (EPA), Region VII. Argonne National Laboratory assisted the CCC/USDA by providing technical oversight for the restoration effort and facilities during this review period. Included in this report are the results of all sampling and monitoring activities performed in accord with the EPA-approved Monitoring Plan for this site (Argonne 2006), as well as additional investigative activities conducted during the …
Date:
June 4, 2009
Creator:
LaFreniere, L. M.
Object Type:
Report
System:
The UNT Digital Library
Reduction of beta* and increase of luminosity at RHIC
The reduction of {beta}* beyond the 1m design value at RHIC has been consistently achieved over the last 6 years of RHIC operations, resulting in an increase of luminosity for different running modes and species. During the recent 2007-08 deuteron-gold run the reduction to 0.70 from the design 1m achieved a 30% increase in delivered luminosity. The key ingredients allowing the reduction have been the capability of efficiently developing ramps with tune and coupling feedback, orbit corrections on the ramp, and collimation, to minimize beam losses in the final focus triplets, the main aperture limitations for the collision optics. We will describe the operational strategy used to reduce the {beta}*, at first squeezing the beam at store, to test feasibility, followed by the operationally preferred option of squeezing the beam during acceleration, and the resulting luminosity increase. We will conclude with future plans for the beta squeeze.
Date:
May 4, 2009
Creator:
Pilat, F.; Bai, M.; Bruno, D.; Cameron, P.; Della Penna, A.; Drees, A. et al.
Object Type:
Article
System:
The UNT Digital Library
High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry
We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.
Date:
March 4, 2009
Creator:
Duden, Thomas & Radmilovic, Velimir
Object Type:
Article
System:
The UNT Digital Library
Beam commissioning of the RFQ for the RHIC-EBIS project
Beam commissioning of a new 4 rod RFQ has started at Brookhaven National Laboratory (BNL). The RFQ will accelerate intense heavy ion beams provided by an Electron Beam ion Source (EBIS) up to 300 keV/u. The RFQ will accelerate a range of Q/M from 1 to 1/6, and the accelerated beam will be finally delivered to the Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL). The first beam was successfully accelerated and the bunch structures of He{sup +} and Cu{sup 10+} beams were measured. The further beam tests are in progress.
Date:
May 4, 2009
Creator:
Okamura,M.; Alessi, J.; Beebe, E.; Lodestro, V.; Pikin, A.; Ritter, J. et al.
Object Type:
Article
System:
The UNT Digital Library
Beam Loss Monitors in the NSLS Storage Rings
Beam loss monitors (BLM) have been used for more than two decades in the VUV ring at the NSLS. These have proved useful for optimizing injection and operation of the ring. Recently similar monitors have been installed in the X-ray ring and are being used to better understand injection, as well as operation of the ring. These units have been compared with the Bergoz BLMs, which have been mostly useful for understanding operating beam losses.
Date:
May 4, 2009
Creator:
Kramer, S. L. & Fedurin, M.
Object Type:
Article
System:
The UNT Digital Library
Beam emittance measurements in RHIC
The RHIC proton polarimeters can operate in scanning mode, giving polarization profiles and transverse beam intensity profile (beam emittance) measurements. The polarimeters function as wire scanners, providing a very good signal/noise ratio and high counting rate. This allows accurate bunch-by-bunch emittance measurements during fast target sweeps (<1 s) through the beam. Very thin carbon strip targets make these measurements practically non-destructive. Bunch by bunch emittance measurements are a powerful tool for machine set-up; in RHIC, individual proton beam transverse emittances can only be measured by CNI polarimeter scans. We discuss the consistency of these measurements with Ionization Profile Monitors (IPMs) and vernier scan luminosity measurements. Absolute accuracy limitations and cross-calibration of different techniques are also discussed.
Date:
May 4, 2009
Creator:
Zelenski,A.; Bazilevsky, A.; Bunce, G.; Gill, R.; Huang, H.; Makdisi, Y. et al.
Object Type:
Article
System:
The UNT Digital Library