Particle Accelerators

The electron paramagnetic resonance (EPR) alanine dosimetry system is based on EPR measurements of radicals formed in alanine by ionizing radiation. The system has been studied to determine its energy dependence for photons in the 10-30 MV region relative to those of 60 Co and to find out if the system would be suitable for dosimetry comparisons. The irradiations were carried out at the National Research Council, Ottawa, Canada and the doses ranged from 8 to 54 Gy. The EPR measurements were performed at the

Quantum efficiency (QE) measurements of single photon photoemission from a Cu(111) single crystal and a Cu polycrystal photocathodes, irradiated by 150fs–6.28eV laser pulses, are reported over a broad range of incidence angle, both in s and p polarizations. The maximum QE (≃4×10−4) for polycrystalline Cu is obtained in p polarization at an angle of incidence θ=65°. We observe a QE enhancement in p polarization which cannot be explained in terms of optical absorption, a phenomenon known as vectorial photoelectric effect. Issues concerning surface roughness and symmetry considerations are addressed. An explanation in terms of nonlocal conductivity tensor is proposed.

This study assesses the dosimetry of a Cobalt-60 (Co 60) teletherapy unit at the Centre for Nuclear Medicine and Radiotherapy (CENAR), Quetta, to ensure consistent radiation doses for cancer management. Dosimetry measurements were compared against expected outputs derived from the International Atomic Energy Agency's TRS-398 protocol and decay calculations. The current investigation demonstrates uniformity in average output (dose rate) between the actual dosimetry values and the anticipated output values obtained through the International Atomic Energy Agency's TRS-398 (2000) protocol and decay method respectively. The actual dosimetry values fall within a range of ±2% of the estimated values. The difference in measurements acquired through the two approaches falls within acceptable limits as per recommended protocols. Consequently, our study reveals a steady pattern in dose rate, ensuring improved patient dose distribution and minimizing the risk of over or under-dosage.

Approximately 70% of commercial industries worldwide use electron accelerator technology for various irradiation processes. The advantages of irradiation processes compared to thermal and chemical processes are higher output levels, reduced energy consumption, less environmental pollution, and producing superior product quality and having unique characteristics that cannot be imitated by other methods. Research Center for Accelerator Technology (PRTA), BRIN, Indonesia is developing standing wave LINAC (SWL) for food irradiation applications at S-band frequencies (±2856 MHz), electron energy of 6-18 MeV, and an average beam power of 20 kW. This paper aims to model, simulate, and analyze the klystron modulator in the RF linear accelerator (LINAC). The klystron modulator is the main component of the RF LINAC, which functions to supply klystron power with the order of megawatt peak DC, so that the klystron can amplify the low-level RF signal from the RF driver into a high-power RF signal with a power of 2-6 MW peak. The klystron modulator modeling is carried out based on mathematical modeling, then simulated using LTspice to analyze the system performance of the klystron modulator. The results of the klystron modulator modeling simulation show stable system performance and dynamic response. So that it meets the specifications of the 6-18 MeV SWL LINAC being developed by PRTA-BRIN.

The commissioning of treatment planning systems and beam modeling requires measured input parameters. The measurement of relative output in-air, Sc is particularly difficult for small fields. The purpose of this study was to investigate the influence of miniphantom design and detector selection on measured Sc values for small fields and to validate the measurements against Monte Carlo simulations. Measurements were performed using brass caps (with sidewalls) or tops (no sidewalls) of varying heights and widths. The performance of two unshielded diodes (60012 and SFD), EBT2 radiochromic film, and a fiber optic dosimeter (FOD) were compared for fields defined by MLCs (5-100 mm) and SRS cones (4-30 mm) on a Varian Novalis linear accelerator. Monte Carlo simulations were performed to theoretically predict Sc as measured by the FOD. For all detectors, Sc agreed to within 1% for fields larger than 10 mm and to within 2.3% for smaller fields. Monte Carlo simulation matched the FOD measurements for all size of cone defined fields to within 0.5%. Miniphantom design is the most important variable for reproducible and accurate measurements of the in-air output ratio, Sc, in small photon fields (less than 30 mm). Sidewalls are not required for fields less than or equal too 30 mm and tops are therefore preferred over the larger caps. Unlike output measurements in water, Scp, the selection of detector type for Sc is not critical, provided the active dosimeter volume is small relative to the field size

Improved treatment techniques in radiation therapy provide incentive to reduce treatment margins, thereby increasing the necessity for more accurate geometrical setup of the linear accelerator and accompanying components. In the present paper, we describe the development of a novel device that enables precise and automated measurement of geometric parameters for the purpose of improving initial setup accuracy, and for standardizing repeated quality control activities. The device consists of a silicon photodiode array, an evaluation board, a data acquisition card, and a laptop. Measurements that demonstrate the utility of the device are also presented. Using the device, we show that the radiation light field congruence for both 6 and 15 MV beams is within 1.3 mm. The maximum measured disagreement between radiation field edges and light field edges was 1.290 ± 0.002 mm, while the smallest disagreement between the light field and radiation field edge was 0.016 ± 0.003 mm. Because measurements are automated, ambiguities resulting from interobserver variability are removed, greatly improving the reproducibility of measurements across observers. We expect the device to find use in consistency measurements on linear accelerators used for stereotactic radiosurgery, during the commissioning of new linear accelerators, or as an alternative to film or other commercially available devices for performing monthly or annual quality control checks.

Improved treatment techniques in radiation therapy provide incentive to reduce treatment margins, thereby increasing the necessity for more accurate geometrical setup of the linear accelerator and accompanying components. In the present paper, we describe the development of a novel device that enables precise and automated measurement of geometric parameters for the purpose of improving initial setup accuracy, and for standardizing repeated quality control activities. The device consists of a silicon photodiode array, an evaluation board, a data acquisition card, and a laptop. Measurements that demonstrate the utility of the device are also presented. Using the device, we show that the radiation light field congruence for both 6 and 15 MV beams is within 1.3 mm. The maximum measured disagreement between radiation field edges and light field edges was 1.290 ± 0.002 mm, while the smallest disagreement between the light field and radiation field edge was 0.016 ± 0.003 mm. Because measurements are automated, ambiguities resulting from interobserver variability are removed, greatly improving the reproducibility of measurements across observers. We expect the device to find use in consistency measurements on linear accelerators used for stereotactic radiosurgery, during the commissioning of new linear accelerators, or as an alternative to film or other commercially available devices for performing monthly or annual quality control checks.

The SPARC project foresees the realization of a free electron laser operating at 500 nm driven by a high brightness photo-injector at a beam energy of 150-200 MeV. The SPARC photoinjector is also the test and training facility for the recently approved VUV/soft X-ray FEL project named SPARX . The second stage of the commissioning, that is currently underway, foresees a detailed analysis of the beam matching with the linac in order to confirm the theoretically prediction of emittance compensation based on the "invariant envelope" matching, the demonstration of the "velocity bunching" technique in the linac and the characterisation of the spontaneous and stimulated radiation in the SPARC undulators. In this paper we report the experimental results obtained so far.

A new strategic plan is in place to upgrade the ALS so it can continue to address fundamental questions, such as size-dependent and dimensional-confinement phenomena at the nanoscale; correlation and complexity in physical, biological, and environmental systems; and temporal evolution, assembly, dynamics and ultrafast phenomena. Moreover, the growing number of ALS users (now exceeding 2,000 per year) requires increased attention. Accordingly, our plan concentrates on projects that will continue to make it possible for ALS users to address grand scientific and technological challenges with incisive world-class tools and quality user support. Our highest priority is to begin top-off operation, in which electrons are injected into the storage ring at intervals of approximately 1 minute. The combination of top-off and concurrent development of small-gap in-vacuum undulators and superconducting undulators will allow an increase in brightness from eight to more than 100 times, depending on the specific undulators and photon energy range. As part of our core mission in the VUV and soft x-ray regions, we plan to exploit these accelerator developments to extend our capabilities for high spatial and temporal resolution and utilize the remarkable coherence properties of the ALS in a new generation of beamlines. Ranked by priority, several proposed beamlines will follow completion of five new beamlines already under construction or funded. The intellectual excitement of the ALS has been a powerful tool in the recruitment and retention of outstanding staff, but additional sustained efforts are required to increase diversity both in gender and in underrepresented groups. To this end, we intend to expand the ALS Doctoral Fellowship Program by giving special emphasis to underrepresented groups. We also envision a distinguished postdoctoral fellowship program with the same emphasis, to increase and diversify our pool of candidates for beamline scientist positions.

Medical physics plays a crucial role in the field of cancer treatment, encompassing various techniques and technologies that aid in diagnosis, treatment planning, and delivery. This comprehensive review aims to provide a thorough examination of the innovations, challenges, and future directions in medical physics as it pertains to cancer treatment. The review begins by discussing the fundamental principles and concepts of medical physics relevant to cancer treatment. It explores the use of radiation therapy, imaging techniques, and other medical physics technologies that contribute to accurate diagnosis and effective treatment. Key advancements in medical physics for cancer treatment are then examined, including the development of intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT), and proton therapy. These innovations have significantly improved treatment precision, reduced side effects, and enhanced patient outcomes. However, along with these advancements come challenges that need to be addressed. The review identifies challenges such as the need for improved radiation dose calculation algorithms, optimization techniques for treatment planning, and quality assurance protocols to ensure patient safety. Additionally, issues related to cost-effectiveness, access to advanced medical physics technologies, and training of medical physicists are discussed. Thus, this comprehensive review underscores the pivotal role of medical physics in cancer treatment. By examining innovations, challenges, and future directions, it provides valuable insights into the advancements that have revolutionized cancer care, the hurdles that need to be overcome, and the potential for further advancements in the field of medical physics. Understanding and addressing these aspects will lead to improved cancer treatment outcomes and enhanced patient care.

SciDAC has had a major impact on computational beam dynamics and the design of particle accelerators. Particle accelerators --which account for half of the facilities in the DOE Office of Science Facilities for the Future of Science 20 Year Outlook --are crucial for US scientific, industrial, and economic competitiveness. Thanks to SciDAC, accelerator design calculations that were once thought impossible are now carried routinely, and new challenging and important calculations are within reach. SciDAC accelerator modeling codes are being used to get the most science out of existing facilities, to produce optimal designs for future facilities, and to explore advanced accelerator concepts that may hold the key to qualitatively new ways of accelerating charged particle beams. In this poster we present highlights from the SciDAC Accelerator Science and Technology (AST) project Beam Dynamics focus area in regard to algorithm development, software development, and applications.

Early laryngeal, especially glottic, cancer is a good candidate for radiotherapy because obvious early symptoms (e.g. hoarseness) make earlier treatment possible and with highly successful localized control. This type of cancer is also a good model for exploring the basic principles of radiation oncology and several key findings (e.g. dose, fractionation, field size, patient fixation, and overall treatment time) have been noted. For example, unintended poor outcomes have been reported during transition from 60 Cobalt to linear accelerator installation in the 1960s, with usage of higher energy photons causing poor dose distribution. In addition, shell fixation made precise dose delivery possible, but simultaneously elevated toxicity if a larger treatment field was necessary. Of particular interest to the radiation therapy community was altered fractionation gain as a way to improve local tumor control and survival rate. Unfortunately, this interest ceased with advancements in chemotherapeutic agents because alternate fractionation could not improve outcomes in chemoradiotherapy settings. At present, no form of acceleration can potentially compensate fully for the lack of concurrent chemotherapy. In addition, the substantial workload associated with this technique made it difficult to add extra fractionation routinely in busy clinical hospitals. Hypofractionation, on the other hand, uses a larger single fractionation dose (2-3 Gy), making it a reasonable and attractive option for T1-T2 early glottic cancer because it can improve local control without the additional workload. Recently, Japan Clinical Oncology Group study 0701 reprised its role in early T1-T2 glottic cancer research, demonstrating that this strategy could be an optional standard therapy. Herein, we review radiotherapy history from 60 Cobalt to modern linear accelerator, with special focus on the role of alternate fractionation.

Beam coupling impedance is a fundamental parameter to characterize the electromagnetic interaction of a particle beam with the surrounding environment. Synchrotron machine performances are critically affected by instabilities and collective effects triggered by beam coupling impedance. In particular, transverse beam coupling impedance is expected to impact beam dynamics of the CERN Proton Synchrotron (PS), since a significant increase in beam intensity is foreseen within the framework of the LHC Injectors Upgrade (LIU) project. In this paper we describe the study of the transverse beam coupling impedance of the PS, taking into account the main sources of geometrical impedance and the contribution of indirect space charge at different energies. The total machine impedance budget, determined from beam-based dedicated machine measurement sessions, is also discussed and compared with the theoretical model.

The production of ~47Gd (T~:2 = 38.1 h) via the ~47Sm(3He,3n)~47Gd and ~44Sm(c~,n)~47Gd processes was investigated. A target system was constructed which allowed irradiation of the target material Sm203 with 15 gA beams of 36 MeV 3He-or 27 MeV ~-particles. A separation technique involving cementation with Na-amalgam followed by an ion exchange process was developed to separate the n.c.a, gadolinium from the bulk of Sm203 target material and from the n.c.a, europium isotopes. Experimental parameters such as sodium content in the amalgam, pH of the solution, Na ÷ concentration in the solution etc., were optimised. The final purification of ~47Gd was done using a small glass column (3 mm gf x 120 mm) or an HPLC column (8 mm gf × 300 mm) filled with a cation exchanger. Using 97% enriched ~47Sm and the separation technique described here about 370-555 MBq (10-15 mCi) 147Gd of high radionuclidic and chemical purity could be achieved. This corresponded to between 40 and 50% of the theoretical batch yield calculated from the excitation function of the t47Sm(3He,3n)~47Gd process. The chemical separation procedure developed also allowed an almost quantitative ( > 90%) recovery of the enriched target material for cyclic use.

General procedures: All reagents were purchased commercially in the highest purity available. N-nitrosodimethylamine and N-nitrosodiethylamine were purchased from Aldrich Chemical Company; N-ethyl-N-methylnitrosamine was purchased from Pfaltz and Bauer. All 1 H NMR spectra were measured in CDCl 3 (7.24 ppm). General procedure for nitramine synthesis: To 5.52 ml (3.06 g, 0.09 mol) of 50% hydrogen peroxide suspended in 100 ml of CH 2 Cl 2 with stirring was added 12.5 ml (18.9 g, 0.09 mol) of trifluoroacetic anhydride in one portion. Since the preparation of the peroxytrifluoroacetic acid in this manner was exothermic, the reaction was most easily conducted at 0 o C. After 10 minutes, the solution was allowed to warm to room temperature, and 7.15 g (7.52 ml, 0.07 mol) of N-S2 nitrosodiethylamine was added dropwise over 15 minutes. During the course of the addition an exothermic reaction occurred, as noted by the boiling of the solution. After the addition was complete the mixture was heated under reflux for an additional four hours. The reaction mixture was then allowed to cool to room temperature, and the dichloromethane was washed twice with water, once with 10% sodium bicarbonate, once again with water, and finally with saturated sodium chloride solution. The organic layer was then dried over magnesium sulfate. Removal of the solvent under reduced pressure yielded 5.47 g (66%) of diethylnitramine as a colorless oil. Dimethylnitramine. Yield 71%. 1 H NMR (CDCl 3 ) δ 3.28 (s, 6H).

The Low Energy ,4ntiproton Ring (LEAR) at CERN is a unique machine which delivers pure antiproton beams over a wide range of kinetic energy (between 2 and 1270MeV) to a large community of physicists. In this paper, we describe the new layout of the experimental areas, designed to fulfil the requirements of the experiments of the "second generation".

On 19th September 2008, during powering tests of the main dipole circuit of the Large Hadron Collider, an electrical fault occurred producing an electrical arc and resulting in mechanical and electrical damage, release of helium from the magnet cold mass to the insulation vacuum enclosure and consequently to the tunnel, via the spring-loaded relief discs on the vacuum enclosure. The

Two dosimetry protocols based on absorbed dose to water have recently been implemented: TG-51 and TRS-398. These protocols use different beam quality indices: %dd(10) x and TPR 20,10 . The effect of electron contamination in measurements of %dd x has been proposed as a disadvantage of the TG-51. For actual measurements of %dd(10) x on five clinical beams (Primus 6-18 MV, SL-75/5 6 MV, SL-18 6-15 MV) a purging magnet was employed to remove the electron contamination. Also, %dd(10) x was measured in the different ways described in TG-51 for high-energy beams: with a lead foil at 50 cm from the phantom surface, at 30 cm, and for open beam. Moreover, TPR 20,10 was determined. Considering both protocols, S w,air and k Q were calculated in order to compare the results with the experimental data. Significant differences (0.3% for k Q ) were only found for the two highenergy beams, but when the electron contamination is underestimated by TG-51, the difference in k Q is lower. Differences in the other cases and variations were less than 0.1%.

Our facility has added high-technology ancillary devices to our dual-energy linear accelerator. After commissioning and acceptance testing of dual asymmetric jaws, dynamic wedge, portal imaging, and multileaf collimation (MLC), quality assurance programs were instituted. The programs were designed to be both periodic and patient specific when required. In addition, when dosimetric aspects were affected by these technologies, additional quality assurance checks were added. Positional accuracy checks (light and radiation) are done for both asymmetric jaws and MLC. Each patient MLC field is checked against the original simulation or digitally reconstructed radiographs. Off-axis factors and output checks are performed for asymmetric fields. Dynamic wedge transmission factors and profiles are checked periodically, and a patient diode check is performed for every new dynamic wedge portal. On-line imaging checks encompass safety checks along with periodic measurement of contrast and spatial resolution. The most important quality assurance activity is the annual review of proper operation and procedures for each device. Our programs have been successful in avoiding patient-related errors or device malfunctions. The programs are a team effort involving physicists, maintenance engineers, and therapists.

Radiochromic film is used extensively in many medical, industrial, and scientific applications. In particular, the film is used in analysis of proton generation and in high intensity laser-plasma experiments where very high dose levels can be obtained. The present study reports calibration of the dose response of Gafchromic EBT3 and HD-V2 radiochromic films up to high exposure densities. A 2D scanning confocal densitometer system is employed to carry out accurate optical density measurements up to optical density 5 on the exposed films at the peak spectral absorption wavelengths. Various wavelengths from 400 to 740 nm are also scanned to extend the practical dose range of such films by measuring the response at wavelengths removed from the peak response wavelengths. Calibration curves for the optical density versus exposure dose are determined and can be used for quantitative evaluation of measured doses based on the measured optical densities. It was found that blue and UV waveleng...

The objective of this study is to evaluate the accuracy of a treatment planning system (TPS) for calculating the dose distribution parameters in conformal fields (CF). Dosimetric parameters of CF's were compared between measurement, Monte Carlo simulation (MCNP4C) and TPS calculation. Materials and Methods: Field analyzer water phantom was used for obtaining percentage depth dose (PDD) curves and beam profiles (BP) of different conformal fields. MCNP4C was used to model conformal fields dose specification factors and head of linear accelerator varian model 2100C/D. Results: Results showed that the distance to agreement (DTA) and dose difference (DD) of our findings were well within the acceptance criteria of 3 mm and 3%, respectively. According to this study it can be revealed that TPS using equivalent tissue air ratio calculation method is still convenient for dose prediction in non small conformal fields normally used in prostate radiotherapy. It was also showed that, since there is a close correlation with Monte Carlo simulation, measurements and TPS, Monte Carlo can be further confirmed for implementation and calculation dose distribution in non standard and complex conformal irradiation field for treatment planning systems.

Introduction: Craniospinal radiotherapy is a therapeutic technique for central nervous system (CNS) tumors, which requires meticulous attention to technique and dosimetry.Treatment planning system (TPS) is one of the main equipment in radiotherapy; therefore, the evaluation of its accuracy is essential for dose calculation. The present study evaluates the validity of Isogray TPS in craniospinal irradiation techniques. Material and Methods: The computed tomography (CT) images of the brain and spine of the Rando phantom were acquired. Two techniques were designed. In technique 1, the whole CNS was irradiated with 6 MV photon beam. In technique 2, the brain and spine were irradiated with 6 MV photon and 18 MeV electron beam, respectively. The tumor and organs at risk doses were measured by thermoluminescent dosimeter (TLD). In addition, photon and electron dose measurements inside and outside the treatment field were accomplished using TLD, and then compared to the corresponding values...

Introduction Wedge modifiers are commonly applied in external beam radiotherapy to change the dose distribution corresponding to the body contour and to obtain a uniform dose distribution within the target volume. Since the radiation dose delivered to the target must be within ±5% of the prescribed dose, accurate dose calculation by a treatment planning system (TPS) is important. The objective of the present study was to quantify the dose calculation accuracy of TiGRT TPS for physical wedged fields in radiotherapy. Materials and Methods A Semiflex™ ionization chamber was used for dose measurements in a water phantom; TiGRT TPS was also applied for dose calculations. The central axis (i.e., high dose-small dose gradient), build-up (i.e., high dose-large dose gradient), off-axis (i.e., high dose-small dose gradient), and out-of-field (i.e., low dose-small dose gradient) regions were evaluated in this study. Finally, the confidence limit values were obtained to quantify the dose calcula...

Aim of the study: Our objective was to quantify the accuracy of dose calculation in the build-up region of the tangential field of the breast for a Ti-GRT treatment planning system (TPS). Material and methods: Thermoluminescent dosimeter (TLD) chips were arranged in a RANDO phantom for the dose measurement. TiGRT TPS was also used for the dose calculation. Finally, confidence limit values were obtained to quantify the accuracy of the dose calculation of the TPS at the build-up region. Results: In the open field, for gantry

The summary of this report is: (1) A high-current SRF cavity for an Energy Recovery Linac (ERL) has been designed by BNL and AES and fabricated by AES; (2) The cavity was cleaned and tested by JLAB with BNL personnel support; (3) Cavity performance exceeded goal of 20 MV/m at Q > 1 x 10¹° and far exceeded requirement of 15 MV/m at Q > 1 x 10¹°; (4) Hermetic String assembled at JLAB with BNL personnel support and shipped to BNL; and (5) BNL has recently completed Cryomodule assembly and unit is ready for installation in the ERL vault.

This paper briefly describes the cryogenic Test capabilities of the Magnet Test Laboratory (MTL). The instrumentation for controlling the operating condition of the magnet cryogenic test and for verifying the requirements of the SSC magnet performance is introduced. The development of the thermometer system, particularly the He vapor preasure thermometers with differential pressure transducer,is presented in detail The 10-kA vapor-cooled power leads were optimized thermally, with consideration for the different fin shapes, diameter, lengths, and RRRs of the power lead material. Two mechanical designs are introduced. The anticryostats, so-called warm bore and warm finger, that provide a warm environment to allow the magnetic fieldmeasuring probe run through the 4.2-K beam tube are described. The warm finger for SSC short-magnet cryogenic tests was manufactured and successfully used. Finally, the feed and end cans-used to provide cryogens to the magnet being tested as well as cryogenic vacuum-and the support of other instrumentation are described.

This paper describes the effective stress on a proposed SSC beam tube. The new issue for the Collider compared to earlier accelerators is the combination of synchrotron radiation with the 4.2-K bore tube of the superconducting magnets [1].One design option is to use a liner within a bore tube to remove the radiated power and the accompanying photodesorbed gas that impair the beam tube vacuum. Design of the SSC 80-K synchrotron radiation liner requires vacuum luminosity lifetime =150 hours and liner electrical conductivity, σ*t > 2E5 Ω-1. [1]. The bimetallic liner tube is subjected to cool down and eddy current loads [2,3]. The liner tube is a two-shell laminate [4] with Nitronic-40 steel for strength and a copper inner layer for low impedance to the image currents induced by the circulating protons. High electrical conductivity of the copper layer is essential for minimizing the power losses. Perforated holes are used to remove the photodesorbed gases for vacuum maintenance. The tube is cooled by 80-K lines. Structural design of the liner is not covered by the ASME code [5]. The life of the liner involves structural integrity and keeping the copper laminate within yield stress limits to maintain the high surface finish for minimizing the power losses, The copper layer stress governs the structural design of the liner. The liner tube analysis is a three dimensional non-linear stress problem. Thermal transient cool down stress [6] is not considered in this analysis because of the floating support design of the liner. This analysis will address the axial thermal stress, non-axisymmetrical eddy current loads, dynamic and nonlinear material effect on the liner that have not been considered in publications on beam tube structural analyses.

The paper reports the efforts that develop a viable design for an SSC 80K Synchrotron Radiation Liner System. The liner is one method under consideration to minimize the presence of photodesorbed gases in the particle beam line vacuum in order to assure an acceptable, operational availability of the SSC Collider. Also the 80K liner is aiming at improving the Collider cryogenic thermal efficiency which would allow a potential luminosity upgrade. The trade studies, engineering analyses, concept evaluation and detailed design are introduced. This paper also briefly discusses the preliminary consideration of lower temperature liners.

An end conductive cooling approach has been developed to reduce the radial space budget of a synchrotron radiation liner to permit the maximum possible liner tube inner diameter (ID). A thermal model has also been developed to analyze the thermal performance of such liners. This approach is found to be acceptable for a liner in a 5 m long quadrupole magnet and 3 m long spool piece, but not for a longer 15 m dipole. The heat transfer and temperature distribution were calculated respectively along the axis of two different liner model: 20K and 80K liner with different thicknesses (0.5-2 mm) of liner tubes and different emissivities (0.05-0.3) of liner surface for a variety of magnets. The thermal model is also applied to the case of an 80K liner connected directly to a 4K beam position monitor (BPM). In order to utilize the end cooling, a good thermal joint and a compact heat exchanger are designed.

This paper describes the response of the eddy current and quench loads on a proposed Superconducting Super Collider 4-K liner system. The liner within a bore tube is designed to remove the radiated power and the photodesorbed gas that impair the beam tube vacuum. 1 The bimetallic liner tube is subjected to cooldown and eddy current loads, 2,3 The square liner tube is a two-shell laminate. 4 Nitronic-40 steel is used for strength and a copper inner layer for low impedaliner to the image currents. Perforated holes are used to remove the photodesorbed gases for vacuum maintenance. The holes are located in a low-stress area of the liner. Rectangular holes in a four-pole symmetry pattern are required for beam dynamic stability. The liner is conductivity cooled by the round steel bore tube with a 2-mm wall. The copper layer must not be stressed over the yield strength limit because copper properties such as conductivity are known to change when the copper is stressed over yield strength. This analysis will address liner system response under thermal, eddy current, and vaporized dynamic helium loads in a quenching dipole magnet.

Single magnet cold testing will be conducted at the Magnet Test Laboratory (MTL) in Waxahachie, Texas. The MTL supports the magnet testing program by providing test capacity for production and R&D dipoles, quadrupoles and specialty magnets Principal components of the cold test stands are the magnet feed and end cans which are closures attached to the open ends of the magnets in order to complete the subsystems of the magnet and allow it to be operated alone. The subsystems of the magnet include the beam pipe, the high field magnet itself with its single-phasc flowing helium environment and its current supply, the cryostat 20 K and 80 K shields, and the cryostat vacuum system. The feed and end cans provide interfaces to the subsystems appropriate for the testing. Thus, they contain feed-throughs for the beam pipe to allow the insertion of the magnetic field measuring system with its warm bore; they contain high current gas-cooled electrical connections for the operation of the coils; they provide cryogenic connections to the various parts of the magnet; they provide the insulating vacuum environment for the magnet; they provide connections to the instrumentation that is a part of the magnet; and they provide instrumentation to characterize the operating conditions under which the testing is performed. Details concerning the present state of the design and development of the feed and end cans will be given.

The spiral-fin, 10-kA, helium vapor-cooled power leads have been designed for Superconducting Super Collider superconducting magnet tests at the Magnet Test Laboratory. In order to thermally optimize the parameters of the power leads, the lead diameters-which minimize the Carnot work for several different lengths, two different fin geometries, and two RRR values of the lead materials-were determined. The cryogenic refrigeration and liquefaction loads for supporting the leads have also been calculated. The optimum operational condition with different currents is discussed. An improved mechanical design of the 10-kA power leads was undertaken, with careful consideration of the cryogenic and mechanical performance. In the design, a new thermal barrier device to reduce heat conduction from the vacuum and gas seal area was employed. Therefore, the electric insulation assembly, which isolates the ground potential parts of the lead from the high-power parts, was moved into a warm region in order to prevent vacuum and helium leakage in the O-ring seals due to transient cold temperature. The instrumentation for testing the power leads is also discussed.

This paper reports on the efforts that have led to the development of a viable design for an SSC 80K Synchrotron Radiation Liner System. The liner is one method under consideration to minimize the presence of photodesorbed gases in the particle beam line vacuum, thereby assuring acceptable operational availability of the SSC Collider. The 80K liner is also aimed at improving the Collider's cryogenic thermal efficiency, which would allow a potential luminosity upgrade. Trade studies, engineering analyses, concept evaluation, and design are introduced. This paper also briefly discusses the preliminary consideration of lower-temperature (20K and 4K) liners.

Inversely planned intensity-modulated radiotherapy (IMRT) and stereotactic small field radiotherapy should be verified before treatment execution. A second verification is carried out for planned treatments in IMRT and 3D conformal radiotherapy (3D-CRT) using a monitor verification commercial dose calculation management software (DCMS). For the same reference point the ion-chamber measured doses are compared for IMRT plans. DCMS (Diamond) computes dose based on modified Clarkson integration, accounting for multi-leaf collimators (MLC) transmission and measured collimator scatter factors. DCMS was validated with treatment planning system (TPS) (Eclipse 6.5 Version, Varian, USA) separately. Treatment plans computed from TPS are exported to DCMS using DICOM interface. Doses are re-calculated at selected points for fields delivered to IMRT phantom (IBA Scanditronix Wellhofer) in high-energy linac (Clinac 2300 CD, Varian). Doses measured at central axis, for the same points using CC13 (0.13 cc) ion chamber with Dose 1 Electrometer (Scanditronix Wellhofer) are compared with calculated data on DCMS and TPS. The data of 53 IMRT patients with fields ranging from 5 to 9 are reported. The computed dose for selected monitor units (MU) by Diamond showed good agreement with planned doses by TPS. DCMS dose prediction matched well in 3D-CRT forward plans (0.8 ± 1.3%, n = 37) and in IMRT inverse plans (-0.1 ± 2.2%, n = 37). Ion chamber measurements agreed well with Eclipse planned doses (-2.1 ± 2.0%, n = 53) and re-calculated DCMS doses (-1.5 ± 2.6%, n = 37) in phantom. DCMS dose validation is in reasonable agreement with TPS. DCMS calculations corroborate well with ionometric measured doses in most of the treatment plans.

A high-resolution separator for the SPIRAL2/DESIR project at GANIL has been designed. The extracted isotopes from SPIRAL2 will be transported to and cooled in a RFQ cooler yielding beams with very low transverse emittance and energy spread. These beams will then be accelerated to 60 keV and sent to a high-resolution mass separator where a specific isotope will be selected. The good beam properties extracted from the RFQ cooler will allow one to obtain a mass resolution of c26000 with the high-resolution mass separator.

Originally the PEP-II injection kickers where powered by one power supply. Since the kicker magnets where not perfectly matched, the stored beam got excited by about 7% of the maximum kicker amplitude. This led to luminosity losses which were especially obvious for trickle injection when the detector is on for data taking. Therefore two independent power supplies with thyratrons in the tunnel next to the kicker magnet were installed. This also reduces the necessary power by about a factor of four since there are no long cables that have to be charged. The kickers are now independently adjustable to eliminate any non-closure of the kicker system and therefore excitation of the stored beam. Setup, commissioning and fine tuning of this system are discussed.

The conventional line type modulators now in use for ELETTRA will have to be replaced for FERMI due to the increase in the pulse repetition frequency (PRF) from 10 to 50 Hz . The requirements for the FERMI modulator are as follows. The klystron which will be used is a Thales TH2132 with a microperviance of 1.9-2.1 uA/V 3/2 . The peak voltage from the modulator is 320 kV, and the current is 350 A. The pulse width is 4.5 us, with a PRF of 50 Hz. Flat top should be better than ±0.5 % of the peak voltage and pulse to pulse ripple better than ±0.1 % of the peak voltage. Prototypes for an upgraded line type modulator and a solid state induction type modulator are in fabrication. The solid state design uses eight induction cells, each cell driven by two parallel Insulated Gate Bipolar Transistors (IGBT). Each IGBT will power an amorphous core with up to 4.16 kV and 1.925 kA for up to 5 us. A single turn is passed through the aperture of each of the cells, inductively adding the pulse voltages. The output from the modulator is then fed to a conventional pulse transformer to reach the 320 kV requirement. This paper presents the system design of both modulator types. Details of the IGBT drivers, control electronics, IGBT and klystron protection and the charging supply for the solid state modulator are also presented.

Radiation therapy is one of many common treatments applied to breast cancer. Most usual radiation sources applied are ionizing radiation, such as γ-rays and X-rays, and non-ionizing radiation such as ultraviolet radiation. The possibility of using near infrared light to photoactivate a drug inside an 8 cm diameter biological object is discussed in this work via Monte Carlo simulations. Two simulation setups performed in the Geant4/GAMOS framework are presented in order to study the viability of photoactivating a drug by using several near infrared light sources. The overall objective of this technique is to minimize energy concentrated at objects surface and maximize it in a predefined region of interest. Results show an increase energy absorption in the desired region of interest inside a 8 cm object, when a higher absorption particle is present. With the use of multiple sources it is possible to photoactivate the drug while causing minimal damage to the surface of the radiated object.

A modified geometry increasing the relative insulating length of NEC tubes has been tested up to 3.3 MV/m. The measured bremsstrahlungs spectra indicate a sufficient particle suppression which agrees with trajectory calculations. Arc discharge cleaning of the tubes was found to be very helpful.

Small concentrations of long-lived ~dioi~topes such as 59Ni are not necessarily easy to determine by AMS because of the background of stable isobars, in this case s9Co. The gas-filled Q3D magnetic spectrograph has been successfully used for isobaric separation. Additional suppression of non-isobaric background is accomplished by means of a Wien filter directly after the tandem and a highly sensitive time-of-flight measurement just before the spectrograph. Until now we have used these techniques for the radioisotopes 41 Ca, s9Ni, 90Sr and lo7Pd. The limits in sensitivity are at present between N 3 x lo-l5 for 41Ca/ Ca and N 1 x lOma for 107Pd/106Pd. Measurements have been performed on environmental, extraterrestrial and nuclear waste samples. Because of the insufficient sensitivity for measurements of very low concentrations with the existing Q3D, a dedicated gas-filled magnet with a deflection angle of 135' is now under constm~ion.

Introduction: This study investigates basic dosimetric properties of unflattened 6 MV photon beam shaped by multileaf collimator and compares them with those of flattened beams. Materials and Methods: Monte Carlo simulation model using BEAM code was developed for a 6MV photon beam based on Varian Clinic 600 unique performance linac operated with and without a flattening filter in beam line. Dosimetric features including lateral profiles, central axis depth dose, photon and electron spectra were calculated for flattened and unflattened cases, separately. Results: An increase in absolute depth dose with a factor of more than 2.4 was observed for unflattened beam which was dependent on depth. PDDs values were found to be lower for unflattened beam for all field sizes. Significant decrease in calculated mlc leakage was observed when the flattening filter was removed from the beam line. The total scatter factor, S CP was found to show less variation with field sizes for unflattened beam indicating a decrease in head scatter. The beam profiles for unflattened case are found to have lower relative dose value in comparison with flattened beam near the field edge, and it falls off faster with distance. Our study showed that increase in the dose rate and lower peripheral dose could be considered as realistic advantages for unflattened 6MV photon beams.

The special issue of JCM on "Advances of MRI in Radiation Oncology" provides a unique forum for scientific literature related to MR imaging in radiation oncology. This issue covered many aspects, such as MR technology, motion management, economics, soft-tissue-air interface issues, and disease sites such as the pancreas, spine, sarcoma, prostate, head and neck, and rectum from both camps-the Unity and MRIdian systems. This paper provides additional information on the success and challenges of the two systems. A challenging aspect of this technology is low throughput and the monumental task of education and training that hinders its use for the majority of therapy centers. Additionally, the cost of this technology is too high for most institutions, and hence widespread use is still limited. This article highlights some of the difficulties and how to resolve them.