Synchrotron Ring Research Articles

A complete low-energy polarized proton-deuteron breakup experiment

An experiment at low energy will be done at the COSY cooler synchrotron and storage ring in order to study the three-particle final states of proton-deuteron scattering reactions measuring a complete set of single and double spin observables over large areas of phase space. The physics objective is to test the predictive power of chiral effective field theory at an energy where convergence is guaranteed and few previous measurements exist. A direct comparison between theoretical predictions and experimental data will be enabled by the use of the so called sampling method.

Results from the Spin Program at COSY-ANKE

It was once claimed that in strong interaction physics “Spin is an inessential complication” [1]. This rather negative attitude ignores certain practical applications and surely dismisses the beauty inherent in many phenomena involving particle polarization. Recognizing this, a program was outlined several years ago to exploit the possibilities of carrying out experiments with polarized beams and targets at ANKE [2]. This facility is based around a magnetic spectrometer sited at an internal target station of the COoler SYnchrotron and storage ring COSY of the Forschungszentrum Jülich. The basic features of the complex were described in a previous issue [3] and we shall here concentrate on a few of the fruits of the spin program.

A fast X-ray detector using silicon avalanche photodiodes of 64-pixel linear array

We have developed a silicon avalanche-photodiode (Si-APD) array detector operated in the linear mode for time-resolved measurements using pulsed synchrotron X-rays. The Si-APD detector had 64 pixels of a linear array, where the pixel size was 100 μm by 200 μm with a 50-μm gap between pixels and a depleted thickness was 10 μm. A nanosecond response of the array detector is extremely valuable for time-resolved X-ray diffraction measurements in the multi-bunch mode operation of a 500M-Hz synchrotron ring. In order to apply the APD detector for the time-resolved diffraction measurements with 2-ns pulse-pair resolving time and a count rate of more than 10 s−1, an ultra fast ASIC has newly been developed for processing a nanosecond-width pulse from each pixel of the Si-APD array. A prototype system had a 10-ns time resolution and a high count-rate of more than 107 s−1/pixel in the first test measurement using synchrotron X-ray beam.

Upgrade of the NSRRC Booster Power Supply

For the 1.5GeV energy injector upgrade project for the NSRRC synchrotron light source, new ramping power supplies were implemented in the “White circuit” booster synchrotron ring. IGBT semiconductors operating at a higher frequency was employed to replace the older GTO-based system. The new system enabled reduction of the current waveform harmonic distortions and thus improving the injection and extraction efficiency. The increased reliability increased blind power from circuit mistuning also ensures higher system uptimes. The measured dynamic range of the 10 Hz sine wave current output of the new ramping power supply is shown to be better than 75 dB with a total harmonic distortion (THD) less than 0.015 %. From the monitored beam current, the low THD dipole magnets current can greatly improve the stability of the booster beam current.

Lattice strain measurements using synchrotron diffraction to calibrate a micromechanical modeling in a ferrite–cementite steel

In situ tensile tests were performed at room temperature on a ferrite–cementite steel specifically designed for this study. The evolution of the average stress in ferrite during loading was analyzed by X-ray diffraction. Lattice strain measurements were performed with synchrotron ring diffraction in both ferrite and cementite. These in situ tests were complemented by macroscopic tensile and reversible tensile-compression tests to study the Bauschinger effect. In order to reproduce stresses in ferrite and cementite particles, a recently developed micromechanical Internal Length Mean Field (ILMF) model based on a generalized self-consistent scheme is applied. In this designed ferrite–cementite steel, the third “phase” of the model represents finite intermediate “layers” in ferrite due to large geometrically necessary dislocation (GND) densities around cementite particles. The assumed constant thickness of the layers is calibrated thanks to the obtained experimental data. The ILMF model is validated by realistic estimates of the Bauschinger stress and the large difference between mean stresses in ferrite and in cementite phases. This difference cannot be reproduced by classic two-phase homogenization schemes without intermediate GND layers.

SU‐C‐224‐09: Energy and Dose Calibration of a Synchrotron‐Produced Monochromatic X‐Ray Beam

Purpose: This work describes planned enhancements to a synchrotron medical radiological beamline, which will improve its efficacy for therapeutic and diagnostic radiological research using monochromatic x‐rays. The primary focus of the present study was the beamlineˈs energy and dose calibrations prior to sample irradiation. This work is crucial for an ongoing study of cell survival of IUdR‐laden cells undergoing photoactivated Auger electron therapy using monochromatic x‐rays. Methods: Calibrations of the monochromatic x‐ray beam are essential for checking the beam energy as well as understanding the variability of the beam quality and dose output. Energy measurements have been performed using Bragg diffraction of a collimated beam from a crystalline silicon powder sample (Si640c). The resulting Debye‐Scherrer diffraction rings were recorded using a digital x‐ray detector. This detector has replaced the use of radiographic film utilized for earlier measurements. Dose measurements of the beam have been performed in a PMMA phantom, using a cylindrical air‐equivalent chamber to measure the dose to water for depths of 0.6 – 10.1 cm. Results: Current results suggest that the beam energy can be measured to within < 0.1 keV. Exposure times of 2 seconds were used to record the Debye‐Scherrer rings, and this has greatly improved upon the 30 – 60 minute exposure times required using radiographic film. The dose rate has been calibrated as a function of the decaying synchrotron ring current, and changes in the beam quality following synchrotron re‐injection have been demonstrated. Conclusions: The use of a digital x‐ray detector has improved the efficiency of the energy measurements. The dose calibration measurements provide a reliable test of the variability of the beam quality and dose output.This research was supported by contract W81XWH‐10‐1‐0005 awarded by The U.S. Army Research Acquisition Activity, 820 Chandler Street, Fort Detrick, MD 21702‐5014. This report does not necessarily reflect the position or policy of the Government, and no official endorsement should be inferred.

Status and future plans of polarized beams at COSY

In this paper we report on the present status and future plans of polarized beams in the COSY synchrotron ring. COSY is a synchrotron ring in the momentum range from 295 to 3700 MeV/c. Polarized deuterons and protons are routinely delivered to experiments over the whole momentum range. No depolarization occurs during the acceleration of deuterons in COSY. For polarized protons many depolarizing resonances are crossed without polarization loss. At imperfection resonances, vertical steerer magnets are used to increase the resonance strength, leading to a complete polarization reversal. At intrinsic resonances a fast tune jump quadrupole is used to quickly cross the resonances without loss of polarization. Typical proton polarizations are close to 0.8 below 2.1 GeV/c and about 0.6 for higher momenta. During recent operation an induced depolarizing resonance was used for accurate determination of the relative momentum spread dp/p of the stored beam yielding an accuracy of better than 10−4. For spin filter studies of the PAX collaboration a low beta target section was installed in 2009 and was successfully put into operation early 2010. An upgrade of the EDDA polarimeter electronics and data acquisition system is underway to ensure continued availability of the polarimeter, which is essential for the polarized proton operation of COSY. In the near future it is planned to install a Siberian snake solenoid of 4.5 Tm to be able to provide in addition to vertically polarized protons, longitudinal polarization as well. This solenoid will allow the preparation of a longitudinally polarized beam up to a kinetic energy of 500 MeV.

The WASA Facility at COSY

The WASA (Wide Angle Shower Apparatus) facility is a 4π detector system for charged and neutral particles that has been designed to study production and decay of light mesons. After successful operation at CELSIUS the facility has started data taking as fixed target internal experiment at the COoler SYnchrotron and storage ring COSY [1] at Forschungszentrum Jülich in 2007. COSY delivers beams of polarized and unpolarized protons and deuterons in the momentum range between 0.3 and 3.7 GeV/c. In collisions with a hydrogen or deuterium target, mesons with masses up to the φ meson can be produced. The WASA detector setup (Figure 1) comprises a forward part to measure charged target-recoil particles and scattered projectiles, a central part to measure meson decay products, and a pellet target.

Installation and diagnostics of a girder-system mockup for Taiwan Photon Source

Taiwan Photon Source (TPS), a new 3 GeV synchrotron ring, is under construction at National Synchrotron Radiation Research Center (NSRRC). To discover problems of design, manufacture and installation, a mockup of 1/24 section (one cell) of TPS was installed at NSRRC. A modified, precise, six-axis, prototype girder system of this mockup composed of three girders was fabricated. We discuss both the installation of the girder system and its diagnostics, and present the results including measurement of the dimensions of the components of the girder system and the vibration tests.

Manufacturing and Operation of the Magnetic Septa for the Slow Beam Extraction From the J-PARC 50 GeV Proton Synchrotron

The magnetic septa have been developed for the slow beam extraction from the 50 GeV Proton Synchrotron to the Hadron Experimental Hall at J-PARC (Japan Proton Accelerator Research Complex). The magnetic septa consist of two thin magnetic septa, four medium thick magnetic septa and four thick magnetic septa. The typical operating current is 3000 A and the total kick angle is 77 mrad with the 30 GeV proton beam. All parts of the thin and of the medium thick septum magnets are made of inorganic materials to resist high radiation environment. The positions of the thin and medium thick septa can be aligned remotely in the horizontal range of ±5 mm, which enables us to minimize the beam loss at the magnetic septum section. The septa were installed in the synchrotron ring in December, 2008, after a test at KEK (High Energy Accelerator Research Organization), and were successfully operated in the beam time for the slow beam extraction in January and February, 2009, which resulted in the first 30 GeV slow extracted beam delivery to the Hadron Experimental Hall.

Innovations in X-Ray Induced Electron Emission Spectrometry (XIEES)

In modern sciences and technologies it is required to investigate local atomic and electron structure of matter independently on its aggregate state. There are advanced methods aimed at short order. These methods are based on the phenomena accompanied by interference of secondary electrons excited by primary X-ray radiation. Such methods are known as XAFS (X-ray absorption fine structure). These methods are based mainly on using of synchrotron radiation. It is realized in two modes: ‘transmission mode’ and registration of secondary effects that follow the primary X-ray absorption. One may announce only two such effects: X-ray induced fluorescence and X-ray induced electron emission (photoeffect). However, the access to synchrotron rings is problematic for the most users. This fact supposes the necessity to develop laboratory devices of direct urgent access. Since the power of laboratory X-ray sources is much less than the flux from synchrotrons, it is necessary to use secondary electron detectors of considerably higher efficiency. Moreover, it is attractive to possess energy in spatial resolution. Channeltrons and multi-channel plates do not have such abilities. That is why the advanced electron detector was developed and exposed to photoeffect under acceleration field. The work is performed within the frames of ISTC Project #3157.

Induction brazing system for cooled conductor joints

This paper is based on the experience gained in the development and setting up of a hard brazing procedure of butt joints by induction heating method, adopted for the manufacturing of copper conductor lengths of rectangular section, with two cooling channels inside. Such conductor has been used by ASG Superconductors for the winding of the resistive coils of the dipole magnets for the Synchrotron Ring at the ‘Centro Nazionale di Adroterapia Oncologica’ of Policlinico S. Matteo Hospital in Pavia. This will be the first such machine in Europe and shall distinguish for the type of particles used (hadrons) and the energy levels applied. This paper describes the contractual requirements, the phases of the selection of the brazing machine, the jigs and tools used for the manufacturing and the tests, the final process adopted and the results obtained.

Design of a Cryogenic Calorimeter for Synchrotron Light Source Beam-Based Heating

Superconducting insertion devices using Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn conductors offer the potential of higher brightness photon beams and enhanced spectral range over existing permanent magnet technology. However, Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn is a low temperature superconductor that must be operated at temperatures near 4.2 K. At these temperatures, any small heat dissipation can potentially be sufficient to lose the superconducting state of a section of a superconducting electromagnet. To quantify the amount of power deposited on the winding emanating from beam-induced heating on a storage ring, we propose a diagnostic calorimeter that will be temporarily integrated into the synchrotron ring. The design of the calorimeter is discussed and the various heat input sources, expected to disturb the operation of a superconducting electromagnet, are reviewed.

Progress with one-coordinate detector for WAXS

Status of the development of a one-coordinate gaseous detector of soft X-ray photons for wide-angle X-ray scattering (WAXS) studies is discussed. The detector operates in a counting mode and is based on a multi-stage Gas Electron Multiplier (GEM). A full size detector has a 67 ∘ aperture at 350 mm from the source. Its readout multi-strip structure has 2048 strips with a 0.2 mm pitch. Main parameters of the detector have been measured with a 8 keV X-ray beam on the VEPP-3 synchrotron ring. A spatial resolution of 470 μ m (FWHM) has been demonstrated that will allow distinguishing diffraction spots at 0 . 1 ∘ .

Automated correction of phase errors in the Advanced Photon Source linac

Maintaining stable phasing in a linear accelerator is crucial for maintaining optimal performance. If phasing is incorrect, the beam will in general have an energy error and increased energy spread. While an energy error can be readily detected and corrected using position readings from beam position monitors at dispersion locations, this method is not useful for correcting energy spread in a system with many possible phase errors. While energy spread can be corrected by looking at beam size at a dispersive location, this typically involves a beam-intercepting diagnostic and is not compatible with top-up operation. Uncorrected energy spread results in poor capture efficiency in downstream accelerators, such as the Advanced Photon Source (APS) particle accumulator ring or booster synchrotron. To address this issue, APS has implemented beam-to-rf phase detectors in the linac, along with software for automatic correction of phase errors. We discuss the design, implementation, and performance of these detectors, as well as their use in feedback to automatically correct linac phase errors during top-up operation.

Development of a one-coordinate gaseous detector for wide angle diffraction studies

A one-coordinate gaseous detector of soft X-ray photonsfor wide-angle X-ray scattering (WAXS) studies is being developed.The detector operates in a counting mode and is based on amulti-stage Gas Electron Multiplier (GEM). A full size detectorhas been assembled. It has a 67-degree aperture at 350 mm from thesource, a readout multi-strip structure with 2048 strips with a0.2 mm pitch. There are some readout electronics in its centralpart. Main parameters of the detector have been measured with a8 keV X-ray beam on the VEPP-3 synchrotron ring. A spatialresolution of 470 μm (FWHM) has been demonstrated. That willallow distinguishing diffraction spots at 0.1 degree.

Production process of alumina-ceramic vacuum chambers for J-PARC

In order to avoid the eddy-current effect due to a rapid-cycling magnetic field in the J-PARC proton synchrotron ring (348 m in circumference), several tens of ceramic chambers (3.5-m long and 500 mm in diameter, at their maximum) are to be installed. The 99.7% alumina ceramic ducts of sub-meter in length, having racetrack and circular cross-sections were sintered and jointed by braze. Several chambers of rectangular and racket-shape cross sections were also produced. A TiN film of 15 nm thick was formed inside the chambers for suppressing secondary electron emission, and electroformed copper stripes were plated outside for lowering the beam-impedance. The course of the production process, including polishing, metallizing and brazing to a titanium flange is reported. Outgassing rates were also measured for a few of the chambers by a conductance-modulation method.

Synchrotron powder X-ray diffractometer beamline at J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices

The J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices (CAMD) is a synchrotron ring operating at 1.3 GeV, with the ring current typically ranging from 230 to 100 mA. An X-ray powder diffraction beamline was recently commissioned at CAMD at the bending magnet port 7A. The powder diffraction beamline consists of a Brazilian-designed double crystal monochromator, a Huber four-circle diffractometer, and a Canberra germanium solid-state detector. The monochromator is equipped with Si 111 and Ge 220 crystals. The Canberra high purity germanium solid-state detector has a resolution of 130 eV at Mn K α. For typical use, the diffractometer circle is set to 17 cm, and the source and receiving slits have been set to 300 and 200 μm, respectively. A sample spinner is used for improved particle size averaging. Wavelength can be shifted in a matter of minutes. Preliminary runs of NIST standards, for example, lanthanum hexaboride (LaB 6) (SRM 660a), show good performance over a wide two-theta range. Rietveld refinement of novaculite (SiO 2) shows lower residual error for the same mineral compared to that obtained from a run with a conventional X-ray source. At the beamline, the user can use MDI's Jade version 7.5 software. The user also has access to International Center for Diffraction Data's Powder Diffraction File-2 database consisting of more than 163,000 inorganic entries and International Crystal Structure Data's crystal structure database with more than 93,000 entries.

Prospects for microbeam radiation therapy of brain tumours in children to reduce neurological sequelae

Microbeam radiation therapy (MRT), a form of experimental radiosurgery of tumours using multiple parallel, planar, micrometres-wide, synchrotron-generated X-ray beams ('microbeams'), can safely deliver radiation doses to contiguous normal animal tissues that are much higher than the maximum doses tolerated by the same normal tissues of animals or patients from any standard millimetres-wide radiosurgical beam. An array of parallel microbeams, even in doses that cause little damage to radiosensitive developing tissues, for example, the chick chorioallantoic membrane, can inhibit growth or ablate some transplanted malignant tumours in rodents. The cerebella of 100 normal 20 to 38g suckling Sprague-Dawley rat pups and of 13 normal 5 to 12kg weanling Yorkshire piglets were irradiated with an array of parallel, synchrotron-wiggler-generated X-ray microbeams in doses overlapping the MRT-relevant range (about 50-600Gy) using the ID17 wiggler beamline tangential to the 6GeV electron synchrotron ring at the European Synchrotron Radiation Facility in Grenoble, France. Subsequent favourable development of most animals over at least 1 year suggests that MRT might be used to treat children's brain tumours with less risk to the development of the central nervous system than is presently the case when using wider beams.

Irradiation of Bypass Diodes up to 2.2E14 Neutron/cm$^{2}$ and 1.3 kGy for the FAIR Project

The FAIR project planned at G.S.I. (Germany) requires the construction of several superconducting accelerator rings. One of the two synchrotron rings, named SIS300, will have dipoles with a central field of 6 T and a ramp rate of 1 T/s. In order to protect these fast-ramping magnets in case of a quench, each of them must be equipped with a diode stack that bypasses the magnet in case it quenches. In order to save time and money on R&D, we decided to use the same diode type as that mounted in LHC magnets. These diodes were previously tested at 77 K up to a fast neutron fluence (F) of 2.8E13 n/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a dose (D) of 2 kGy which are the expected radiation loads after 20 years of LHC operation. Having no definitive estimation of the losses in the SIS300, we arbitrarily targeted a fluence of 1E14 n/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . We irradiated six LHC type diodes at 77 K in six steps. The highest values measured were 1.31 kGy and 2.25E14 n/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Before and after each irradiation step, the forward and reverse voltage characteristics of each diode were measured. This paper reports the results of these measurements, carried out at ITEP (Moscow).