Compton Backscattering Research Articles

Beam Dynamics Investigation for a New Project of Compton Back Scattering Photon Source at NRNU MEPhI

Beam Dynamics Investigation for a New Project of Compton Back Scattering Photon Source at NRNU MEPhI

Circular electron-positron collider beam energy measurement scheme based on microwave-electronic Compton backscattering

The accurate calibration of the beam energy of the circular electron-positron collider (CEPC) is performed to accurately measure the mass width of Higgs particle and the mass of W/Z boson, thus providing the basic experimental basis for the accurate test of the standard model. Based on this, the error control of beam energy is required to be at a level of 10<sup>–5</sup>. Compton backscattering method is suitable for high precision calibration of beam energy in the Hundred GeV high energy electron collider. In this work, the CEPC beam energy is predicted to reach a theoretical accuracy of about 3 MeV by using the accurate measurement of the scattered photon energy after microwave electron Compton backscattering. Firstly, TM<sub>01</sub> mode microwave transmission in circular waveguide is selected according to the design requirements, and the electromagnetic field distribution and Poynting vector under this condition are solved. According to the photon distribution and transmission in the waveguide, the design idea is proposed to simplify the complexity of calculation, and the parameters conforming to the design requirements are solved by combining the simultaneous equations of the high purity germanium detector sensitivity and the background of synchrotron radiation. Using the optimal set of waveguide inner diameter, microwave wavelength and electron incident angle data, the derivative of the differential scattering cross section with respect to energy and the collision brightness are obtained when the microwave power is 100 W. The scattered photon density of 15 MeV energy is further obtained, and the signal-to-noise ratio is analyzed according to the photon density of synchrotron radiation under this energy. The feasibility of the scheme is demonstrated theoretically and the technical difficulties and problems to be further studied are discussed.

Development of a position-sensitive fast scintillator (LaBr3(Ce)) detector setup for gamma-ray imaging application

We have characterized a Cerium doped Lanthanum Bromide (LaBr3(Ce) ) crystal coupled with the position-sensitive photo-multiplier system for the gamma-ray imaging application. One can use this detector set-up for the scanning of high purity germanium detectors for pulse shape analysis in gamma-ray spectroscopy experiments and the image formation of an object by Compton back-scattering . The sensor has been tested for energy, timing and position information of the gamma-rays interacting within the detector crystal. The GEANT4 simulation results are consistent with the experimental results. We have reconstructed the image of irradiation spots in different positions throughout the detector crystal. Position resolution is found to be around 3.5 mm with the 2 mm collimated gamma-rays. The 2-d image of hexagonal Bismuth Germanate (BGO) crystal and a cylindrical LaBr3(Ce) crystal have been reconstructed in coincidence technique. The performance of the detector for imaging application has been investigated by coincidence technique in GEANT4 simulation and compared with the experimental data. We have reconstructed the 2-d images of objects with various geometrical shapes by Compton back-scattered events of the gamma-rays. This position-sensitive detector can be used as an absorber of a Compton camera for the image reconstruction of an extended radioactive source. One can also use this kind of set-up as in radiation imaging and many other applications where the energy and source position of the gamma-ray is the main interest.

Deconvolution of Mono-Energetic and Multi-Lines Gamma-Ray Spectra Obtained with NaI(Tl) Scintillation Detectors Using Direct Matrix Inversion Method

Performance of a NaI(Tl) scintillation detector based on the gamma-ray spectroscopy system is not satisfactory in retaining its original peak (which is delta like function) of various gamma ray spectrum. The method of achieving precise peak for the various gamma ray was conducted by converting the observed pulse-height distribution of the NaI(Tl) detector to a true photon spectrum. This method is obtained experimentally with the help of an inverse matrix deconvolution method. The method is based on response matrix generated by the Monte Carlo simulation based on Geant4 package of mono-energy gamma-ray photon ranging from 0.050 to 2.04 MeV in the interval of 10 keV. The comparison of the measured and simulated response function was also performed in order to authenticate the simulation response function. Good agreement was observed around the photo-peak region of the spectrum, but slight deviation was observed at low energy region especially below 0.2 MeV. The Compton backscattering and Compton continuum counts was significantly transferred into the corresponding photo-peak and consequently the peak to total(P/T) ratio was improved. The P/T ratio results obtained after application of the deconvolution method taken with three calibration sources with gamma-ray’s energies of 81 keV, 303 keV and 356 keV (for 133Ba), 662 keV (for 137Cs), 1173 keV and 1333keV (for 60Co), were improved from(to) 0.50(0.90), 0.40(0.83), 0.57(0.93), 0.31(0.92), 0.18(0.84) and 0.15(0.83), respectively.

A new method for measuring the space between two metal plates using a Compton backscattering method

Determining the space between two metal plates by accessing only one side of the configuration can be difficult, especially when we are not able to use methods with the need to have direct contact with the plates. In such a condition, using gamma-ray based approaches can be beneficial. In this paper, a new method based on Compton scattering of the gamma-rays was proposed to measure the gap between two metal plates and the related challenges were studied. Steel plates with 1, 4, and 10 mm thicknesses were selected to test the proposed method. The results showed that this method needs a low activity gamma-ray source and can be employed successfully for this purpose. It was found that the accuracy of the method the thickness of the plates and the distance between them.

Design of prototype Front-End Electronics for the Gamma-Gamma collider

The Gamma-Gamma collider is a scientific facility proposed in China to observe two unique interactions at the center-of-mass energy of 1–2 MeV, namely γγ scattering and electron-positron pairs. In the experiment, two γ beams generated by the Compton back-scattering of high-energy electron beams (∼200 MeV) and high-intensity laser beams will collide at the interaction point, and the products will be collected by CsI(Na) crystals and plastic scintillators, and then converted into electric signals by silicon photomultiplier (SiPM) detectors. In this paper, a prototype Front-End Electronics (FEE) is implemented to verify the design requirements concerning the noise level (no more than 3 mV), high sampling rate (1 GS/s) and low power consumption. The prototype FEE comprised 8 differential drivers, 2 low-power switch capacitor array (SCA) DRS4 chips, and an 8-channel Analog-to-Digital Converter (ADC). The input signals were first stored in DRS4 chips for time stretching, then digitized by the ADC, and finally sent to back-end electronics via an optical link. The noise (RMS) of each readout channel on the prototype FEE was less than 3 mV after offset correction, and the ENOB of the channels was better than 6.7 bit when the frequency of input sine waves was less than 70 MHz and the sampling rate of the DRS4 was 1 GS/s. Therefore, the performance of the prototype FEE meets the requirements of the Gamma-Gamma collider.

Analysis of the Aperture Function of the Scattering Volume of the Collimation System of the Scattering Computed Tomography of Steel Products with a Ring Detector

This article discusses the features of the collimation system of a tomograph for monitoring steel products by Compton backscattering. The analysis of the aperture functions of the scattering volume for the ring-type detector with different sizes of the pinholes of the primary and secondary collimators is carried out. The efficiency of using a ring type detector is shown. Recommendations to select pinhole sizes of the primary and secondary collimators are given. An indirect estimation of the possible scanning depth of steel products is given.

Multiple-Collision Free-Electron Laser Compton Backscattering for a High-Yield Gamma-Ray Source

We observed multiple-collision free-electron laser (FEL)-Compton backscattering in which a multi-bunch electron beam makes head-on collisions with multi-pulse FELs in an optical cavity, using an infrared FEL system in the storage ring NIJI-IV. It was demonstrated that the measured spectrum of the multiple-collision FEL-Compton backscattering gamma rays was the summation of the spectra of the gamma rays generated at each collision point. Moreover, it was demonstrated that the spatial distribution of the multiple-collision FEL-Compton backscattering gamma rays was the summation of those of the gamma rays generated at each collision point. Our experimental results proved quantitatively that the multiple collisions in the FEL-Compton backscattering process are effective in increasing the yield of the gamma rays. By applying the multiple-collision FEL-Compton backscattering to high-repetition FEL devices such as energy recovery linac FELs, an unprecedented high-yield gamma-ray source with quasi-monochromaticity and wavelength tunability will be realized.

The Compton electron beam Polarimeter for the AmPS ring

The longitudinal polarization of the stored electron beam in the AmPS ring will be measured through the laser Compton backscattering technique. With the outlined design the measurement of the expected 70% degree of polarization to a statistical precision of 3% requires less than 60 sec under ideal conditions.

Calculating Parameters of Pinhole in Collimation System of Albedo Computed Tomography of Steel Products

We examine specific features of the collimation system of a tomograph for testing steel products based on Compton backscattering. The device is described and the parameters of the primary pinhole collimator of the collimation system are calculated. The device allows reliable scanning of a steel test object by simply displacing the pinhole perpendicular to the X-ray axis from the tube anode within 50 mm with a focal length of 163 mm.

Feasibility studies of an all-optical and compact γ-ray blaster using a 1 PW laser pulse

Recently, the all-optical Compton laser backscattering setup has become a promising approach in producing high-quality γ-rays. However, this method only produces a single γ-ray beam. In this paper, we report on the numerical study for the feasibility of producing double γ-ray beams using a 1 PW laser. Our method utilizes the all-optical setup with a structured solid target as a reflecting foil. The laser pulse is reflected by the foil after propagating a few millimeters into the underdense plasma. The reflected laser intensity is strongly boosted by the foil to invoke a radiation reaction as nonlinear Compton backscattering. Subsequently, the electron bunch traverses the foil, generating bremsstrahlung. Our simulation results show that a collimated γ-ray beam from the nonlinear Compton backscattering with the peak brilliance of 6.7 × 1020 photons/s/mm2/mrad2/0.1% BW at 15 MeV is produced. Another collimated γ-ray beam with the peak brilliance of 2.1 × 106 photons/s/mm2/mrad2/0.1% BW is produced by bremsstrahlung. The combined γ-ray beams act as a blaster and are of particular interest in nuclear interactions induced by high-energy photons.

Semi-empirical method for determining the density of liquids using a NaI(Tl) scintillation detector

In this study, we developed a new method for determining the density of liquids using the Compton backscattering technique. The principle of this method is based on the change in the area under a single scattering peak versus the liquid density. The linear calibration curve of the ratio R versus the density is required to determine the density of an unknown liquid (R is the ratio of the area under a single scattering peak for a liquid relative to that for water). In the proposed method, the calibration curve is completely constructed based on a simulation using the MCNP5 code. The method involves combining a simulation with an experiment as a semi-empirical method. Using this method, we determined the density of four liquids comprising acetonitrile, glycerol, nitric acid, and sulfuric acid, and the maximum deviations between the reference densities and measured values were less than 1.4%, except in the case of sulfuric acid, which was approximately 4.5%. The results obtained in this study strongly suggest that the proposed method is suitable and feasible for application.

Laser-Particle Collider for Multi-GeV Photon Production.

As an alternative to Compton backscattering and bremsstrahlung, the process of colliding high-energy electron beams with strong laser fields can more efficiently provide both a cleaner and brighter source of photons in the multi-GeV range for fundamental studies in nuclear and quark-gluon physics. In order to favor the emission of high-energy quanta and minimize their decay into electron-positron pairs, the fields must not only be sufficiently strong, but also well localized. We here examine these aspects and develop the concept of a laser-particle collider tailored for high-energy photon generation. We show that the use of multiple colliding laser pulses with 0.4PW of total power is capable of converting more than 18% of multi-GeV electrons passing through the high-field region into photons, each of which carries more than half of the electron initial energy.

High density γ-ray emission and dense positron production via multi-laser driven circular target

A diamond-like carbon circular target is proposed to improve γ-ray emission and pair production with a laser intensity of 8 × 1022 W cm−2 by using 2D particle-in-cell simulations with quantum electrodynamics. It is found that the circular target can enhance the density of γ-photons significantly more than a plane target, when two colliding circularly polarized lasers irradiate the target. By multi-laser irradiating the circular target, the optical trap of lasers can prevent the high energy electrons accelerated by laser radiation pressure from escaping. Hence, γ-photons with a high density of beyond 5000nc are obtained through nonlinear Compton backscattering. Meanwhile, 2.7 × 1011 positrons with an average energy of 230 MeV are achieved via the multiphoton Breit–Wheeler process. Such an ultrabright γ-ray source and dense positron source can be useful in many applications. The optimal target radius and laser mismatching deviation parameters are also discussed in detail.

Status of ELI-NP and opportunities for hyperfine research

The status of the implementation of the Extreme Light Infrastructure – Nuclear Physics (ELI-NP) facility is reported. The main instruments at ELI-NP will be two 10 PW synchronizable lasers and a high-brilliance gamma beam system. The ELI-NP gamma beams will be produced via Compton back-scattering of laser photons off accelerated electrons. The emerging day-one experimental program is discussed, together with the detector systems which are under construction for its realization. At ELI-NP an IGISOL facility is planned, where beams of exotic nuclei will be produced in photo-fission. This opens the avenue for studies of nuclear structure studies, such as mass measurements, nuclear moments and charge radii. The core of this project is a Cryogenic Stopping Cell (CSC) with an orthogonal extraction with respect to the gamma beam.

Design and dynamic studies for a compact storage ring to generate gamma-ray light source based on Compton backscattering technique

As the development of nuclear physics and atomic sciences progresses, monochromatic and high-flux gamma-ray light sources are highly demanded by many experiments in these fields. We have designed a compact storage ring for gamma-ray source generation based on the Compton backscattering technique. The energy range of the electron beam stored in the ring will be from 500 to 800 MeV, with the capability of generating a gamma ray with an energy range from about 4 to 10 MeV. The maximum energy loss for an electron could be more than 1% for one scattering event, which could have a significant impact on electron beam dynamics. To study this impact, a 6D macroparticle tracking code has been developed by including the Compton scattering, damping, quantum excitation, and synchrotron radiation in the storage ring. The equilibrium states have been studied with this code, and the results show good agreement with theoretical predictions. The electron beam loss rate induced by Compton scattering has also been investigated by varying the input laser beam parameters. This study allows us to optimize the storage ring operation for a stable, high-flux, and narrow-bandwidth gamma-ray beam generation.

Tau mass measurement at BES-III

A scan of the threshold region of the process e+ e−→ τ+τ− with integrated luminosity about 140 pb−1 was performed with the BES-III detector at the BEPC-II collider in order to measure the τ-lepton mass. The beam energy was determined by the Compton backscattering method. To verify the measurement accuracy scans of the J/ψ and ψ′ resonances were performed.

Detection of scales and its thickness determination in industrial pipes using Compton backscattering system.

The ability to detect and quantify scales in pipes has been an important yardstick for efficient transfer of fluids in domestic as well as in application related industries. Knowledge of different kinds of scales formed has become a precondition for trouble-shooting in operational lines. In this paper, collimated Compton backscattered gamma rays from a radioactive source have been used to inspect the scales by automatic scanning in steps along the axial direction of different pipes. The methodology has been extended for the quantification of scales that prevails in the real functionality of extensive usage of fluids. To aid for descaling processes, the desideratum is the density determination of scales and this parameter is quantified non-destructively and is also validated with the standard density. The described non-intrusive gamma ray densitometry is quite promising, efficient and has highly reliable results for scale detection with the squared correlation coefficient of 0.98. The proposed technique shows a better linearity than the gammatography technique.

Review of the ELI-NP-GBS low level rf and synchronization systems

The Gamma Beam System (GBS) of ELI-NP is a linac based gamma-source in construction at Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy and with intensity and brilliance well beyond the state of the art will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV) and a 515 nm intense laser pulse. Production of very intense photon flux with narrow bandwidth requires multi-bunch operation at 100 Hz repetition rate. A total of 13 klystrons, 3 S-band (2856 MHz) and 10 C-band (5712 MHz) will power a total of 14 Travelling Wave accelerating sections (2 S-band and 12 C-band) plus 3 S-band Standing Wave cavities (a 1.6 cell RF gun and 2 RF deflectors). Each klystron is individually driven by a temperature stabilized LLRF module, for a maximum flexibility in terms of accelerating gradient, arbitrary pulse shaping (e.g. to compensate beam loading effects in multi-bunch regime) and compensation of long-term thermal drifts. In this paper, the whole LLRF system architecture and bench test results, the RF reference generation and distribution together with an overview of the synchronization system will be described.

OA192] Kilovoltage rotational radiotheraphy with the marix/brixs source for partial breast irradiation

Purpose The development of compact sources of high brilliance, mono-chromatic, tunable X-rays with energy in the range 30–150 keV is a topical research field; applications in radiodiagnostics are foreseen. The aim of this work is to propose the use of a compact source based on X-ray Compton back-scattering (also known as Inverse Compton Source, ICS) developed within the MariX/BriXS project [1] , for kilovoltage rotational radiotherapy dedicated to the breast. Methods The proposed source is based on a modified Tigner scheme of push-and-pull twin Super-Conducting Energy Recovery Linacs, just wrapped on itself in order to halve the overall length of the machine. The ICS source was simulated by using the code CAIN and the output X-ray photon beam was obtained. The anticipated performances are a flux up to 1013 photons/s within 5% bandwidth, coming in radiation pulses a few psec long at a repetition rate up to 100 MHz, fully tunable in the 20–150 keV energy range with full control of polarization and adjustable bandwidth in the range 0.5–10%. The simulated X-ray spectrum was used as an input of a previously validated Monte Carlo Geant4 code to calculate the dose distribution in a 50/50 breast phantom during a rotational radiotherapy scan. The pendant breast was modelled as a cylinder of 14 cm diameter and 9 cm height irradiated over 360 deg at 88 keV average energy and a 1-cm tumor was simulated at the isocenter. Results The dose distribution obtained with the kilovoltage beam generated by the ICS source shows that it is possible to perform a partial breast irradiation with dose levels to the target and to the skin, compatible with clinical treatments using conventional linacs. Conclusions We proposed the application of a Compton back-scattering X-ray source for kilovoltage rotational radiotherapy for breast cancer. The technique could be useful for partial breast irradiation with or without injection of a dose enhancement agent, for radiosurgery of small size breast tumors.