Quasi-monochromatic gamma-ray beams are produced in the laser Compton slant-scattering at the Shanghai Laser Electron Gamma Source (SLEGS) of the Shanghai Synchrotron Radiation Facility. A high-power CO(2 )laser is operated in Gated CW mode in a wide range of pulse repetition frequencies of 1-100 kHz and pulse width > 1 mu s. The Gated CW operation of the CO(2 )laser generates pulse gamma-ray beams with a variety of time structure and gamma flux. We report fundamental laser properties in the Gated CW operation and the gamma flux in two cases of gamma-ray beams suited to nuclear physics experiments and industrial applications.

Basing on the slant Compton scattering of 10640 nm photons from a 100 W CO2 laser on 3.5 GeV electrons from the Shanghai Light Source, the Shanghai Laser Electron Gamma Source (SLEGS) produces gamma-ray in the energy range of 0.66 MeV–21.7 MeV and flux of 105–107 photons/s. A Gamma Modulation System (GMS) composed of the collimators, attenuator, beam spot imaging(MiniPIX) and flux monitor(LaBr3 detector) was developed to ensure producing bandwidth-variable quasi-monochromatic gamma-ray with a variable-flux at same time. Using the GMS, variable-flux quasi-monochromatic gamma-ray beams with a best bandwidth of 10% in the 90∘ slant-scattering and 4% in back-scattering were obtained respectively. We report on the performance of the GMS and results of gamma-ray beam modulating measurement with GMS at SLEGS.

The Gamma Spot Monitor(GSM) at SLEGS beamline is designed to provide a direct view of the gamma beam profile. The main part of the GSM is a LYSO crystal and an astronomical camera. A set of experimental tests on its performance were carried out. The results show that the magnification are 21.0% in X and 21.2% in Y direction, and the relative distortion is proved to be lower than 0.7%. The spatial resolution of the GSM evaluated by the Modulation Transfer Function(MTF) is better than 6.4 lp/mm. The contrast resolution is better than 14%. Beamline alignment is essential in beam modulation, and there are several ways for beamline alignment. In this paper, alignment capability of the GSM is demonstrated, also, the absorption coefficient distribution of a model composed of different materials is shown.

Total-energy responses of a 76 mm × 200 mm BGO detector were used to deduce energy distributions of quasi-monoenergetic gamma-rays generated at the Shanghai Laser Electron Gamma Source (SLEGS) of the Shanghai Synchrotron Radiation Facility. Responses of the BGO detector to monoenergetic gamma-rays produced in (p,γ) reactions on LiF, 27Al, and 13C targets were measured at the China Institute of Atomic Energy. A direct unfolding of BGO total-energy responses into gamma-ray energy distributions was iteratively performed by solving a set of linear equations with the monoenergetic response of the BGO detector being the matrix element. We present resultant energy distributions of gamma-ray beams produced in the slant-scattering at SLEGS.

The conflict between the production capacity and demand for medical radioisotopes has become more prominent. In addition, for some new types of medical radioisotopes, neutron, and proton-induced reactions are not the best way to generate them with high specific activity. The research status of medical radioisotopes is introduced, then the gamma facility and potential new medical radioisotope candidates based on photonuclear reaction are widely surveyed. The production of medical radioisotope 186gRe is simulated based on the Laser Compton Scattering (LCS) gamma source and bremsstrahlung gamma source. It is found that the next generation quasi-monochromatic, high-flux LCS gamma source can produce medical radioisotope 186gRe with less than 0.05% 188Re impurity with around 400 mb cross section. Meanwhile, the bremsstrahlung gamma source can produce around 200 MBq/g specific activity medical radioisotope 186gRe with realistic electron intensity 3.125 mA. This study and simulations show that photonuclear reaction can be regarded as an alternative route for producing medical radioisotopes.

Basing on the inverse Compton scattering of 10640 nm photons from a 100 W CO2 laser on 3.5 GeV electrons from the Shanghai Light Source, Shanghai laser electron gamma source (SLEGS) produces gamma-rays in the energy range of 660 keV-21.7 MeV with a flux of 10(5)-10(7) photons/s. A new annular collimator system was designed to extend the low energy range of SLEGS to 100 keV. Gamma-ray beams in the extended range are quasimonochromatic and with a best possible bandwidth of 13.96% with the flux larger than 10(4) photons/s. The new annular collimator will expand the application areas, and constitutes a critical component of the SLEGS. The Geant4 simulations show that the annular collimator equipped at the experiment hutch is effective in extending energy range and turning bandwidths.

Energy-variable gamma-rays are produced in the laser Compton slant-scattering in the Shanghai laser electron gamma source (SLEGS) beamline of the Shanghai Light Source. An interaction chamber composed of the rotating laser optical system, shielding finger, and reference-target insertion device was developed to ensure slant scattering in the angular range of 20-160, producing gamma-rays in the energy range of 0.66-21.1 MeV with a flux of 4.8 x 10(5)-1.5 x 10(7) photons/s. SLEGS is the first slant-scattering beamline which systematically produces energy-variable gamma-ray beams and continuously tune the gamma-ray energy in the laser Compton slant-scattering. We report on designed performance of the slant-scattering and results of a test run.

To assess the efficacy and safety of drug-eluting beads transarterial chemoembolization (DEB-TACE) in liver cancer patients with different times of previous conventional transarterial chemoembolization (cTACE) treatments.

Gamma-ray polarimetry is a new powerful tool to study the processes responsible for the emission from astrophysical sources and the environments in which this emission takes place. Few successful polarimetric measurements have however been performed thus far in the gamma-ray energy band due to the difficulties involved. POLAR is a dedicated polarimeter designed to perform high precision measurements of the polarization of the emission from gamma-ray burst in the 50-500 keV energy range. This new polarimeter is expected to detect approximately 50 gamma-ray bursts per year while performing high precision polarization measurements on approximately 10 bursts per year. The instrument was launched into lower earth orbit as part of the second Chinese space lab, the Tiangong-2, on September 15th 2016 and has been taking data successfully since being switched on one week after. The instrument uses a segmented scintillator array consisting of 1600 plastic scintillator bars, read out by 25 flat-panel multi-anode photomultipliers, to measure the Compton scattering angles of incoming photons. The small segmentation and relatively large uniform effective area allow the instrument to measure the polarization of a large number of transient events, such as gamma-ray bursts, with an unprecedented precision during its two year life-time. The final flight model underwent detailed calibration prior to launch as well as intensive space qualification tests, a summary of which will be presented in this paper. The instrument design will be discussed first followed by an overview of the on-ground tests, finally the in-orbit behavior as measured during the first weeks of the mission will be presented.

The Gamma-ray Burst Polarimeter-POLAR is a highly sensitive detector which is dedicated to the measurement of GRB’s polarization with a large effective detection area and a large field of view (FOV). The optimized performance of POLAR will contribute to the capture and measurement of the transient sources like GRBs and Solar Flares. The detection energy range of POLAR is 50 keV ~ 500 keV, and mainly dominated by the Compton scattering effect. POLAR consists of 25 detector modular units (DMUs), and each DMU is composed of low Z material Plastic Scintillators (PS), multi-anode photomultipliers (MAPMT) and multi-channel ASIC Front-end Electronics (FEE). POLAR experiment is an international collaboration project involving China, Switzerland and Poland, and is expected to be launched in September in 2016 onboard the Chinese space laboratory “Tiangong-2 (TG-2)”. With the efforts from the collaborations, POLAR has experienced the Demonstration Model (DM) phase, Engineering and Qualification Model (EQM) phase, Qualification Model (QM) phase, and now a full Flight Model (FM) of POLAR has been constructed. The FM of POLAR has passed the environmental acceptance tests (thermal cycling, vibration, shock and thermal vacuum tests) and experienced the calibration tests with both radioactive sources and 100% polarized Gamma-Ray beam at ESRF after its construction. The design of POLAR, Monte-Carlo simulation analysis, as well as the performance test results will all be introduced in this paper.

Gamma Ray Bursts (GRBs) are the strongest explosions in the universe which might be associated with creation of black holes. Magnetic field structure and burst dynamics may influence polarization of the emitted gamma-rays. Precise polarization detection can be an ultimate tool to unveil the true GRB mechanism. POLAR is a space-borne Compton scattering detector for precise measurements of the GRB polarization. It consists of a 40×40 array of plastic scintillator bars read out by 25 multi-anode PMTs (MaPMTs). It is scheduled to be launched into space in 2016 onboard of the Chinese space laboratory TG2. We present a dedicated methodology for POLAR calibration and some calibration results based on the combined use of the laboratory radioactive sources and polarized X-ray beams from the European Synchrotron Radiation Facility. They include calibration of the energy response, computation of the energy conversion factor vs. high voltage as well as determination of the threshold values, crosstalk contributions and polarization modulation factors.

OBJECTIVE:To study the prognosis of large hepatocellular carcinoma after interventional radiology and to compare the efficacy of different microinvasive treatments. PATIENTS AND METHODS:The clinical data of 46 large hepatocellular carcinoma patients confirmed by clinical treatment or pathological examination were retrospectively analyzed. Patients were divided into two groups (TACE+RFA n=23 cases, and Combination group n=23 cases), according to the treatments method. two groups were followed up for 5-48 months. Survival was estimated using the Kaplan-Meier method and the survival curve was compared by log-rank test. RESULTS:Median follow-up time was 33 months in both groups. The median survival time in Combination group (n=41 months) was significantly longer than TACE+RFA group (n=33 months) (p = 0.052). Median progress-free survival (PFS) is 10 months in Combination group and 8 months in TACE+RFA group. The difference was statistically significant (p = 0.023). The tumor inhibition rate was 82.6% and 52.2%, respectively and the difference was statistically significant (p = 0.028). The overall survival rate at l, 2 and 3 years was 100%, 95.7% and 55.8% respectively in Combination group was higher than TACE+RFA group at 91.3%, 55.8% and 38.3% respectively. The difference was not statistically significant. CONCLUSIONS:For large hepatocellular carcinoma, combined method was superior to TACE+RFA and comprehensive treatment can improve the local-control rate.

In-depth studies of solar flares emissions and energy releases include analyses of polarization data. Polarization gives clear information about mechanisms and processes leading to electron acceleration and photon production. Despite of many past attempts, the key energy range of hard X-rays was only rarely explored and results were inconclusive. To large extend it was due to greater instrumental complications. Currently several novel polarimeters are either to be employed or under constructions for both balloon and satellite based observations. The novel hard X-ray polarimeter POLAR is an instrument developed by a collaboration between Switzerland, China and Poland. It is primarily designed for high accuracy polarization measurements from the prompt photon emissions of the gamma-ray bursts. The satellite orientation and instrument pointing direction make it also capable for precise measurements of polarization in solar flares. The instrument should fly in near future onboard of the Chinese Space Station TG2.

Human leukocyte antigen (HLA)-G molecule acts as a potential factor for the regulation of immune responses and its expression in virus-infected cells may enable them to escape immunosurveillance. Besides its polymorphic promoter region, the 3' untranslated region (UTR) seems to play an important role in regulating HLA-G expression. In this study, we investigated the influence of HLA-G 14 bp (rs66554220) and +3142 (rs1063320) polymorphisms in 179 women with active human papillomavirus (HPV) infection and 143 age-matched, unrelated, HPV-negative, normal Chinese Han population. Our findings showed that frequency of the allele +3142 C [31.3% vs 44.4%, odds ratio (OR) = 0.57, P-c < 0.01] and the genotype +3142 CC (10.6% vs 21.7%, OR = 0.43, P-c = 0.012) was significantly decreased in HPV infected patients compared with normal controls. Furthermore, the haplotype -14 bp/C was associated with a reduced risk for HPV infection (OR = 0.57, P-c = 0.001). Our findings also showed that HLA-G homozygous + 14 bp/+ 14 bp genotype was significantly associated with an increased risk for HPV18 infection (OR = 12.95, P < 0.01), whereas HLA-G heterozygous + 14 bp/-14 bp genotype increased risk for HPV58 (OR = 5.55, P < 0.05). Furthermore, frequency of the haplotype + 14 bp/G was significantly increased in HPV18 infected patients (60.0% vs 27.3%, OR = 4.00, P-c < 0.05). Taken together, our results supported a role of the HLA-G 3' UTR polymorphisms as a susceptible factor for the active HPV infection, and suggested a possible interference of the HLA-G molecule in the response to virus infection.

Measurements of polarisation of gamma-rays emitted in Gamma-Ray Burst (GRB) will provide a new parameter in collected data. This parameter is sensitive to predictions of different models of poorly known gamma-ray emission processes. Here, we present the POLAR experiment - a compact space detector dedicated to the measurement of polarisation of GRB gamma-rays prompt emission. The flight model of POLAR will be ready in 2014, for launch in space by 2015 on the Chinese Spacelab TG-2. Expected lifetime of experiment is 3 years.

For Nd: LaxLu1-xVO4 (x = 0.05) crystal, the F-4(3/2) -> 2 -> I-4(3/2) transition property was investigated for the first time. The fluorescence peak of Nd: La0.05Lu0.95VO4 crystal exhibited inhomogeneous broadening comparing with that of Nd: LuVO4 crystal. With a laser diode array as the pump source, continuous- wave (CW) and active/passive Q-switched laser operation based on the F-4(3/2) -> I-4(13/2) transition was realized. For CW laser operation, the maximum output powers of 0.561 and 0.718 W were obtained with slope efficiencies of 11.3% and 12.5% and optical- to- optical conversion efficiencies of 8.9% and 7.7%, respectively, for a and c cut crystal samples. For acousto- optic/ passively Q- switched laser operation, the shortest pulse width, highest peak power and maximum pulse energy reached 44 ns, 273 W and 12 similar to J, and 41 ns, 199 W and 8 : 2 similar to J, respectively. Our research has indicated that Nd:LaxLu1-xVO4 is a promising gain medium for mode- locked laser operation at 1 : 34 mu m.

The unsteady Reynolds-averaged Navier-Stokes equations with the k-ω based SST turbulence model were solved to model the unsteady flow within the entire flow passage of a large Francis Pump turbine with misaligned guide vanes (MGV) device under the rotated speed. Four MGV with three different MGV openings are chosen to analyse the influence of pressure pulse in turbine modes. This study investigates the characteristics of the dominant unsteady flow frequencies in different parts of the pump turbine for various MGV openings. The hydraulic performance and pressure fluctuations were predicted numerically. The computed result shows that the MGV can decrease the relative amplitude in the state part of flow passage, but not for the rotator runner blades.

We combine a simulation program for Laser Compton Scattering (LCS) with another for deuteron photodisintegration to simulate an experiment to search for parity violation in the d((gamma) over right arrow, n)p reaction using a LCS source. We extract the differential cross-section for d((gamma) over right arrow, n)p near threshold from fits to all relevant available d((gamma) over right arrow, n)p experimental data. We use this information along with theoretical estimates of parity violation in this reaction to calculate neutron yields and PV asymmetries in d((gamma) over right arrow, n)p near threshold using the weight method. This work lays a foundation for us to study the feasibility of this experiment, the optimization of experimental conditions, and systematic effects and false asymmetries in detail. (c) 2013 Elsevier B.V. All rights reserved.

The main performance challenge of POLAR - a novel hard X-ray polarimeter, is to achieve high statistical accuracy and large modulation factors. Both require great level of response uniformity. Though, typical sensitivity of multi-anode PMTs may vary between its channels up to the factor of two to three. Moreover, the measured signal can be further altered by light coupling quality. We investigate response equalization based on utilizing of an optical mask with light-blocking diaphragms. It is placed between scintillator bars and the PMT photo-cathode. Each PMT channel-pad is equipped with the unique diaphragm with its area related to the initial sensitivity of the corresponding channel. We present module/mask construction details, test setup and measurement results done before and after applying of the mask corrections. Applicability of the method is discussed with respect to the instrument dynamic range, low energy threshold requirements and aging effects due to the in-space utilization.