73 Matching Results

Search Results

Advanced search parameters have been applied.

IMPROVEMENT OF CdMnTe DETECTOR PERFORMANCE BY MnTe PURIFICATION

Description: Residual impurities in manganese (Mn) are a big obstacle to obtaining high-performance CdMnTe (CMT) X-ray and gamma-ray detectors. Generally, the zone-refining method is an effective way to improve the material's purity. In this work, we purified the MnTe compounds combining the zone-refining method with molten Te, which has a very high solubility for most impurities. We confirmed the improved purity of the material by glow-discharge mass spectrometry (GDMS). We also found that CMT crystals from a multiply-refined MnTe source, grown by the vertical Bridgman method, yielded better performing detectors.
Date: April 25, 2011
Creator: Kim, K. H.; Bolotnikov, A. E.; Camarda, G. S.; Tappero, R.; Hossain, A.; Cui, Y. et al.
Partner: UNT Libraries Government Documents Department

NSLS-II Transport Line Progress

Description: The National Synchrotron Light Source II (NSLS-II) is a state-of-the-art 3-GeV third generation light source currently under construction at Brookhaven National Laboratory. The NSLS-II injection system consists of a 200 MeV linac, a 3-GeV booster synchrotron and associated transfer lines. The first part of the Linac to Booster Transport (LBT) line has been installed for linac commissioning. This part includes all components necessary to commission the NSLS-II linac. The second part of this transport line is undergoing installation. Initial results of hardware commissioning will be discussed. The Booster to Storage Ring (BSR) transport line underwent a design review. The first part of the BSR transport line, consisting of all components necessary to commission the booster will be installed in 2012 for booster commissioning. We report on the final design of the BSR line along with the plan to commission the booster.
Date: May 20, 2012
Creator: P., Fliller R.; Wahl, W.; Anderson, A.; Benish, B.; DeBoer, W.; Ganetis, G. et al.
Partner: UNT Libraries Government Documents Department

Optimisation of NSLS-II Blade X-ray Beam Position Monitors: from Photoemission type to Diamond Detector

Description: Optimisation of blade type x-ray beam position monitors (XBPM) was performed for NSLS-II undulator IVU20. Blade material, con and #64257;guration and operation principle was analysed in order to improve XBPM performance. Optimisation is based on calculation of the XBPM signal spatial distribution. Along with standard photoemission type XBPM a Diamond Detector Blades (DDB) were analysed as blades for XBPMs. DDB XBPMs can help to overcome drawbacks of the photoemission blade XBPMs.
Date: July 10, 2012
Creator: P., ILINSKI
Partner: UNT Libraries Government Documents Department

PHYSICS RESULTS OF THE NSLS-II LINAC FRONT END TEST STAND

Description: The Linac Front End Test Stand (LFETS) was installed at the Source Development Laboratory (SDL) in the fall of 2011 in order to test the Linac Front End. The goal of these tests was to test the electron source against the specifications of the linac. In this report, we discuss the results of these measurements and the effect on linac performance.
Date: May 20, 2012
Creator: P., Fliller R.; Gao, F.; Yang, X.; Rose, J.; Shaftan, T. & Piel, C
Partner: UNT Libraries Government Documents Department

Proceedings of Pulsed Magnet Design and Measurement Workshop

Description: The goals of the Workshop are to assess the design of pulsed system at the NSLS-II and establish mitigation strategies for critical issues during development. The focus of the Workshop is on resolving questions related to the set-up of the pulsed magnet laboratory, on measuring the pulsed magnet's current waveforms and fields, and on achieving tight tolerances on the magnet's alignment and field quality.
Date: January 19, 2010
Creator: Shaftan, T.; Heese, R. & Ozaki,S.
Partner: UNT Libraries Government Documents Department

CONTROL OF NONLINEAR DYNAMICS BY ACTIVE AND PASSIVE METHODS FOR THE NSLS-II INSERTION DEVICES

Description: Nonlinear effects from insertion devices are potentially a limiting factor for the electron beam quality of modern ring-based light sources, i.e., the on and off-dynamical aperture, leading to reduced injection efficiency and beam lifetime. These effects can be modelled by e.g. kick maps ({approx}1/{gamma}{sup 2}) and controlled by e.g. first-order thin or thick magnetic kicks introduced by 'magic fingers,' 'L-shims,' or 'current strips'. However, due to physical or technological constraints, these corrections are typically only partial. Therefore, a precise model is needed to correctly minimize the residual nonlinear effects for the entire system. We outline a systematic method for integrated design and rapid prototyping based on evaluation of the 3D magnetic field and control of the local trajectory with RADIA, and particle tracking with Tracy-3 for validation. The optimal geometry for the compensating magnetic fields is determined from the results of these simulations using a combination of linear algebra and genetic optimization.
Date: May 20, 2012
Creator: J., Bengtsson; Chubar, O.; Kitegi, C. & Tanabe, T.
Partner: UNT Libraries Government Documents Department

CALCULATING POINT-CHARGE WAKEFIELDS FROM FINITE LENGTH BUNCH WAKE-POTENTIALS

Description: Starting from analytical properties of high frequency geometric impedance we show how one can accurately calculate short bunch wake-potentials (and even point-charge wakefields) from time domain calculations performed with a much longer bunch. In many practical instances this drastically reduces the need for computer resources, speeds up the calculations, and improves their accuracy. To illustrate this method we give examples for 2D accelerator structures of various complexities. We describe preliminary results of a new method that allows us to accurately obtain longitudinal wakefields of short bunches by adding a long-bunch result from an EM solver and a singular analytical wake model. In the future this work will be generalized to 3D geometries as well. Similarly, the method should be equally applicable to the calculations of transverse wakefields. Periodic structures with a significant number of periods (2 {ge} a{sup 2}/{sigma}L, where L is the period length) have not been considered so far. They have asymptotic wakefields that differ from the examples described above. We believe this method is applicable to such geometries as well, as long as correct asymptotic solutions are used.
Date: March 28, 2011
Creator: Podobedov, B. & Stupakov, G.
Partner: UNT Libraries Government Documents Department

FINAL DESIGN OF ILC RTML EXTRACTION LINE FOR SINGLE STAGE BUNCH COMPRESSOR

Description: The use of single stage bunch compressor (BC) in the International Linear Collider (ILC) Damping Ring to the Main Linac beamline (RTML) requires new design for the extraction line (EL). The EL located downstream of the BC will be used for both an emergency abort dumping of the beam and the tune-up continuous train-by-train extraction. It must accept both compressed and uncompressed beam with energy spread of 3.54% and 0.15% respectively. In this paper we report the final design that allowed minimizing the length of such extraction line while offsetting the beam dumps from the main line by 5m distance required for acceptable radiation level in the service tunnel. Proposed extraction line can accommodate beams with different energy spreads at the same time providing the beam size suitable for the aluminum ball dump window. We described the final design of the ILC RTML extraction line located downstream of the new single-stage bunch compressor. The extraction line is only 24m long and is capable of accepting and transmitting 220kW of beam power. The EL can be used for both fast intra-train and continual extraction, and is capable of accepting both 0.15% and 3.54% energy spread beams at 5MeV and 4.37MeV respectively.
Date: March 28, 2011
Creator: Seletskiy, S. & Solyak, N.
Partner: UNT Libraries Government Documents Department

MULTIOBJECTIVE DYNAMIC APERTURE OPTIMIZATION AT NSLS-II

Description: In this paper we present a multiobjective approach to the dynamic aperture (DA) optimization. Taking the NSLS-II lattice as an example, we have used both sextupoles and quadrupoles as tuning variables to optimize both on-momentum and off-momentum DA. The geometric and chromatic sextupoles are used for nonlinear properties while the tunes are independently varied by quadrupoles. The dispersion and emittance are fixed during tunes variation. The algorithms, procedures, performances and results of our optimization of DA will be discussed and they are found to be robust, general and easy to apply to similar problems.
Date: March 28, 2011
Creator: Yang, L.; Li, Y.; Guo, W. & Krinsky, S.
Partner: UNT Libraries Government Documents Department

National Synchrotron Light Source 2010 Activity Report

Description: This is a very exciting period for photon sciences at Brookhaven National Laboratory. It is also a time of unprecedented growth for the Photon Sciences Directorate, which operates the National Synchrotron Light Source (NSLS) and is constructing NSLS-II, both funded by the Department of Energy's Office of Science. Reflecting the quick pace of our activities, we chose the theme 'Discovery at Light Speed' for the directorate's 2010 annual report, a fiscal year bookended by October 2009 and September 2010. The year began with the news that NSLS users Venki Ramakrishnan of Cambridge University (also a former employee in Brookhaven's biology department) and Thomas A. Steitz of Yale University were sharing the 2009 Nobel Prize in Chemistry with Ada E. Yonath of the Weizmann Institute of Science. Every research project has the potential for accolades. In 2010, NSLS users and staff published close to 900 papers, with about 170 appearing in premiere journals. Those are impressive stats for a facility nearly three decades old, testament to the highly dedicated team keeping NSLS at peak performance and the high quality of its user community. Our NSLS users come from a worldwide community of scientists using photons, or light, to carry out research in energy and environmental sciences, physics, materials science, chemistry, biology and medicine. All are looking forward to the new capabilities enabled by NSLS-II, which will offer unprecedented resolution at the nanoscale. The new facility will produce x-rays more than 10,000 times brighter than the current NSLS and host a suite of sophisticated instruments for cutting-edge science. Some of the scientific discoveries we anticipate at NSLS-II will lead to major advances in alternative energy technologies, such as hydrogen and solar. These discoveries could pave the way to: (1) catalysts that split water with sunlight for hydrogen production; (2) materials that can ...
Date: December 29, 2010
Creator: Rowe, M. & Snyder, K. J.
Partner: UNT Libraries Government Documents Department

PERFORMANCE OF THE DIAGNOSTICS FOR NSLS-II LINAC COMMISSIONING

Description: The National Synchrotron Light Source II (NSLS-II) is a state of the art 3-GeV third generation light source currently under construction at Brookhaven National Laboratory. The NSLS-II injection system consists of a 200 MeV linac, a 3-GeV booster synchrotron and associated transfer lines. The transfer lines not only provide a means to deliver the beam from one machine to another, they also provide a suite of diagnostics and utilities to measure the properties of the beam to be delivered. In this paper we discuss the suite of diagnostics that will be used to commission the NSLS-II linac and measure the beam properties. The linac to booster transfer line can measure the linac emittance with a three screens measurement or a quadrupole scan. Energy and energy spread are measured in a dispersive section. Total charge and charge uniformity are measured with wall current monitors in the linac and transformers in the transfer line. We show that the performance of the diagnostics in the transfer line will be sufficient to ensure the linac meets its specifications and provides a means of trouble shooting and studying the linac in future operation.
Date: March 28, 2011
Creator: Fliller III, R.; Padrazo, D.; Wang, G.M.; Heese, R.; H.-C., Hseuh; Johanson, M. et al.
Partner: UNT Libraries Government Documents Department

NSLS-II BPM System Protection from Rogue Mode Coupling

Description: Rogue mode RF shielding has been successfully designed and implemented into the production multipole vacuum chambers. In order to avoid systematic errors in the NSLS-II BPM system we introduced frequency shift of HOM's by using RF metal shielding located in the antechamber slot of each multipole vacuum chamber. To satisfy the pumping requirement the face of the shielding has been perforated with roughly 50 percent transparency. It stays clear of synchrotron radiation in each chamber.
Date: March 28, 2011
Creator: Blednykh, A.; Bach, B.; Borrelli, A.; Ferreira, M.; Hseuh, H.-C.; Hetzel, C. et al.
Partner: UNT Libraries Government Documents Department

NSLS-II HIGH LEVEL APPLICATION INFRASTRUCTURE AND CLIENT API DESIGN

Description: The beam commissioning software framework of NSLS-II project adopts a client/server based architecture to replace the more traditional monolithic high level application approach. It is an open structure platform, and we try to provide a narrow API set for client application. With this narrow API, existing applications developed in different language under different architecture could be ported to our platform with small modification. This paper describes system infrastructure design, client API and system integration, and latest progress. As a new 3rd generation synchrotron light source with ultra low emittance, there are new requirements and challenges to control and manipulate the beam. A use case study and a theoretical analysis have been performed to clarify requirements and challenges to the high level applications (HLA) software environment. To satisfy those requirements and challenges, adequate system architecture of the software framework is critical for beam commissioning, study and operation. The existing traditional approaches are self-consistent, and monolithic. Some of them have adopted a concept of middle layer to separate low level hardware processing from numerical algorithm computing, physics modelling, data manipulating, plotting, and error handling. However, none of the existing approaches can satisfy the requirement. A new design has been proposed by introducing service oriented architecture technology. The HLA is combination of tools for accelerator physicists and operators, which is same as traditional approach. In NSLS-II, they include monitoring applications and control routines. Scripting environment is very important for the later part of HLA and both parts are designed based on a common set of APIs. Physicists and operators are users of these APIs, while control system engineers and a few accelerator physicists are the developers of these APIs. With our Client/Server mode based approach, we leave how to retrieve information to the developers of APIs and how to use them to form ...
Date: March 28, 2011
Creator: Shen, G.; Yang; L.; Shroff & K.
Partner: UNT Libraries Government Documents Department

NSLS-II INJECTION STRAIGHT DIAGNOSTICS

Description: The ultra-bright light source being developed by the NSLS-II project will utilize top-up injection and fine tuning of the injection process is mandatory. In this paper we present the diagnostics installed in the injection straight. Its use for commissioning and tuning of the injection cycle is also described. The NSLS-II storage ring will utilize a 9.3 meter long injection straight section shown in Fig. 1. Injection will be preformed with two septa (one pulsed, one DC) and four kickers. The stored beam will be shifted towards the pulsed septum up to IS mm and the nominal distance between centers of the injected and the bumped beam is 9.5mm. The NSLS-II beam position monitors will have turn-by-turn and first-turn capabilities and will be used for the commissioning and tuning the injection process. However, there are three additional BPMs and two beam intercepting OTR screens (flags) installed in the injection straight.
Date: March 28, 2011
Creator: Pinayev, I.; Blednykh, A.; Ferreira, M.; Fliller, R.; Kosciuk, B.; Shaftan, T.V. et al.
Partner: UNT Libraries Government Documents Department

NSLS-II: Nonlinear Model Calibration for Synchrotrons

Description: This tech note is essentially a summary of a lecture we delivered to the Acc. Phys. Journal Club Apr, 2010. However, since the estimated accuracy of these methods has been naive and misleading in the field of particle accelerators, i.e., ignores the impact of noise, we will elaborate on this in some detail. A prerequisite for a calibration of the nonlinear Hamiltonian is that the quadratic part has been understood, i.e., that the linear optics for the real accelerator has been calibrated. For synchrotron light source operations, this problem has been solved by the interactive LOCO technique/tool (Linear Optics from Closed Orbits). Before that, in the context of hadron accelerators, it has been done by signal processing of turn-by-turn BPM data. We have outlined how to make a basic calibration of the nonlinear model for synchrotrons. In particular, we have shown how this was done for LEAR, CERN (antiprotons) in the mid-80s. Specifically, our accuracy for frequency estimation was {approx} 1 x 10{sup -5} for 1024 turns (to calibrate the linear optics) and {approx} 1 x 10{sup -4} for 256 turns for tune footprint and betatron spectrum. For a comparison, the estimated tune footprint for stable beam for NSLS-II is {approx}0.1. Since the transverse damping time is {approx}20 msec, i.e., {approx}4,000 turns. There is no fundamental difference for: antiprotons, protons, and electrons in this case. Because the estimated accuracy for these methods in the field of particle accelerators has been naive, i.e., ignoring the impact of noise, we have also derived explicit formula, from first principles, for a quantitative statement. For e.g. N = 256 and 5% noise we obtain {delta}{nu} {approx} 1 x 10{sup -5}. A comparison with the state-of-the-arts in e.g. telecomm and electrical engineering since the 60s is quite revealing. For example, Kalman filter (1960), crucial for ...
Date: October 8, 2010
Creator: Bengtsson, J.
Partner: UNT Libraries Government Documents Department

COMPENSATION OF FAST KICKER ROLLS WITH SKEW QUADRUPOLES

Description: The development of the third generation light sources lead to the implementation of the top-up operation, when injection occurs while users collect data. The beam excursions due to the non-closure of the injection bump can spoil the data and need to be suppressed. In the horizontal plane compensation can be achieved by adjusting timing and kick amplitudes. The rolls of the kicker magnets create non-closure in the vertical plane and usually there is no means for correction. In the paper we describe proposed compensation scheme utilizing two skew quadrupoles placed inside the injection bump. The third generation light sources implement top-up operation firstly introduced at Advanced Photon Source. In this mode the circulating beam current is supported near constant by frequent injection of small charge, while photon beam is delivered for users. The beam perturbations caused by the mismatched injection bump can provide undesired noise in the user data. Usually the injection trigger is distributed to the users end stations so that those affected would be able to blank data acquisition. Nevertheless, as good operational practice such transients should be suppressed as much as possible. In the horizontal plane (which is commonly used for injection) one can adjust individual kicker strength as well as trigger delay while observing motion of the stored beam centroid. In the vertical plane such means are unavailable in the most cases. The possible solutions include dedicated weak vertical kickers and motorized adjustment of the roll angle of the injection kickers. Both abovementioned approaches are expensive and can significantly deteriorate reliability. We suggest two employ two skew quadrupoles (to correct both angle and position) placed inside the injection bump. In this case the beam position itself serves as measure of the kicker strength (assuming that kickers are well matched) and vertical kicks from the skew quadrupoles ...
Date: March 28, 2011
Creator: Pinayev, I.
Partner: UNT Libraries Government Documents Department

CURRENT STATUS OF INSERTION DEVICE DEVELOPMENT AT THE NSLS-II AND ITS FUTURE PLANS

Description: National Synchrotron Light Source-II (NSLS-II) project is currently under construction. Procurement of various insertion devices (IDs) has begun. This ring assumes a very high beam stability requirement which imposes tighter field specifications on insertion devices (IDs) compared to the rings of previous generation. The state of the art ID Magnetic Measurement Facility is being set up in order to be able to certify the stringent requirements on the magnetic field of NSLS-II IDs. The IDs in the project baseline scope include six 3.5m long damping wigglers (DWs) with 100mm period length and 15mm pole gap, two 2.0m Elliptically Polarizing Undulator (EPU) with 49mm period and 11.5mm minimum magnetic gap, two 3.0m long 20mm period and one 1.5m long 21mm period IVU, which the minimum gap of these is 5mm and 5.5mm, respectively. Recently a special device for inelastic X-ray scattering (IXS) beamline has been added to the collection of baseline devices. Three pole wigglers with a 28mm magnetic gap and a peak field over 1 Tesla will be utilized to accommodate the users of the type of radiation which is currently produced with bending magnets at the NSLS.
Date: March 28, 2011
Creator: Tanabe, T.; Chubar, O.; Corwin, T.; Harder, D.A.; He, P.; Kitegi, C. et al.
Partner: UNT Libraries Government Documents Department

Comparison of 1D and 2D CSR Models with Application to the FERMI@ELETTRA Bunch Compressors

Description: We compare our 2D mean field (Vlasov-Maxwell) treatment of coherent synchrotron radiation (CSR) effects with 1D approximations of the CSR force which are commonly implemented in CSR codes. In our model we track particles in 4D phase space and calculate 2D forces [1]. The major cost in our calculation is the computation of the 2D force. To speed up the computation and improve 1D models we also investigate approximations to our exact 2D force. As an application, we present numerical results for the Fermi{at}Elettra first bunch compressor with the configuration described in [1].
Date: March 28, 2011
Creator: Bassi, G.; Ellison, J.A. & Heinemann, K.
Partner: UNT Libraries Government Documents Department

ADDITIONAL QUADRUPOLES AT CENTER OF LONG STRAIGHTS IN THE NSLS-II LATTICE

Description: The NSLS-II storage ring lattice is comprised of 30 DBA cells arranged in 15 superperiods. There are 15 long straight sections (9.3m) for injection, RF and insertion devices and 15 shorter straights (6.6m) for insertion devices. In the baseline lattice, the short straights have small horizontal and vertical beta functions but the long straights have large horizontal beta function optimized for injection. In this paper, we explore the possibility of installing additional quadrupoles at the center of selected long straight sections in order to provide two low-beta source locations for undulators in the same straight. The required modification to the linear lattice is discussed as well as the preservation of adequate dynamic aperture required for good injection efficiency and adequate Touschek lifetime. This paper discusses the possibility of producing two low-beta source locations for optimum brightness of undulators in the long straights of NSLS-II lattice by installing additional quadrupoles at the center. The linear optics is optimized to satisfy the requirements of lattice function and properties. Nonlinear optimization for a lattice with working point at (37.16, 17.22) is performed. Considering the magnets misalignment errors and physical apertures, we calculate the frequency maps and plot the tune footprint. The results show that the modified high-low beta function lattice can achieve a modest dynamic aperture in this preliminary study. Further work will continue to expand the dynamic aperture to meet the requirement of good injection efficiency and sufficient Touschek lifetime.
Date: March 28, 2011
Creator: Lin, F.; Bengtsson, J.; Guo, W.; Krinsky, S.; Li, Y. & Yang, L.
Partner: UNT Libraries Government Documents Department

IMPLEMENTATION OF A DC BUMP AT THE STORAGE RING INJECTION STRAIGHT SECTION

Description: The NSLS II beam injection works with a DC septum, a pulsed septum and four fast kicker magnets. The kicker power supplies each produce a two revolution period pulsed field, 5.2 {micro}s half sine waveform, using {approx}5kA drive voltage. The corresponding close orbit bump amplitude is {approx}15mm. It is desired that the bump is transparent to the users for top-off injection. However, high voltage and short pulse power supplies have challenges to maintain pulse-to-pulse stability and magnet-to-magnet reproducibility. To minimize these issues, we propose implementing a DC local bump on top of the fast bump to reduce the fast kicker strength by a factor of 2/3. This bump uses two storage ring corrector magnets plus one additional magnet at the septum to create a local bump. Additionally, these magnets could provide a DC bump to simulate the septum position effects on the store beam lifetime. This paper presents the detail design of this DC injection bump and related beam dynamics.
Date: March 28, 2011
Creator: Wang, G.M.; Shaftan, T.; Kramer, S.K.; Fliller, R.; Guo, W.; Heese, R. et al.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier

Description: We report experimental studies of the effect of undulator tapering on superradiance in a single-pass high-gain free-electron laser (FEL) amplifier. The experiments were performed at the Source Development Laboratory (SDL) of National Synchrotron Light Source (NSLS). Efficiency was nearly tripled with tapering. Both the temporal and spectral properties of the superradiant FEL along the uniform and tapered undulator were experimentally characterized using frequency-resolved optical gating (FROG) images. Numerical studies predicted pulse broadening and spectral cleaning by undulator tapering Pulse broadening was experimentally verified. However, spectral cleanliness degraded with tapering. We have performed first experiments with a tapered undulator and a short seed laser pulse. Pulse broadening with tapering expected from simulations was experimentally confirmed. However, the experimentally obtained spectra degraded with tapering, whereas the simulations predicted improvement. A further numerical study is under way to resolve this issue.
Date: March 28, 2011
Creator: Hidaka, Y.; She, Y.; Murphy, J.B.; Podobedov, B.; Seletskiy, S. & Yang, X.
Partner: UNT Libraries Government Documents Department