Vol.25,

For developing the X-ray Free Electron Lasers test facility (SXFEL) at Shanghai Institute of Applied Physics, Chinese Academy of Sciences (SINAP), ultra-short bunch is the crucial requirement for excellent lasing performance. It is a big challenge for deflecting cavity to measure the length of ultra-short bunch, and higher deflecting gradient is required for higher measurement resolution. X-band travelling wave deflecting structure has features of higher deflecting voltage and compact structure, which has good performance at ultra-short bunch length measurement. In this paper, a new X-band deflecting structure is designed to operate in HEM11-2π/3 mode. For suppressing the polarization of deflecting plane of the HEM11 mode, two symmetrical caves are added on the cavity wall to separate two polarized modes.

507

Surface preparation is an important processing in production procedures of superconducting niobium cavities, deciding whether the performance of the niobium cavities can meet the specifications. A series of surface preparation methods and relevant apparatuses have been constructed at Shanghai Institute of Applied Physics (SINAP) and the standard procedures of cavity processing were established and successfully applied to different types of cavities. With standard surface preparation procedures on the 500 MHz 5-cell niobium cavity, the cavity accelerating voltage at T=4.2 K reached 7.5 MV while its quality factor was still higher than 1×10⁹. The accelerating gradient of the IMP-HWR010 cavity reached 4.9 MV/m with the quality factor of better than 3×10⁸ at 4.2 K.

597

In building Shanghai Synchrotron Radiation Facility (SSRF), in order to reduce or eliminate the unnecessary sources of beam motion, the precise and stable beam position measurement system in the feedback system was required. In this study, we focused on theoretical analysis of the electrode of beam position monitor (BPM). Simulations, including analytic derivations of the propagation impedance and the distribution inductance, were performed. The BPM was designed based on the results and the acceptance measurements of the impedance and the inductance by using the time domain reflection (TDR) with a network analyzer. It has been proved in years of operations that the BPM system meets the requirement of the resolution of sub-micron.

370

Recently we measured with the Modified Three Gradient Method (MTGM) [1, 2] the beam emittance of an injector constructed in 2012, which was designed to provide a 2.4 kA, 2.6 MeV electron beam. The MTGM is a non-intercept indirect method, which is based on the three gradient type measurements of beam profiles and subsequent data processing which helps to get the least square solution to the beam emittance. Beam profiles under different currents of guiding coil are measured using Cerenkov radiation given off by a piece of quartz glass in the beam tube, which is recorded with a CCD camera. MTGM Code is developed to realize the data fitting as well as beam transport simulation, in which both the σ matrix method and the numerical solution of root-mean-square beam envelope equation are used. The error is also analyzed.

476

In order to improve aerodynamic performance and efficiency, monitoring the geometry and position information of the internal structure with the aero-engine under various operational statuses is an important task. In this paper, a novel design of industrial computed tomography (ICT) system with a linac as x-ray source is proposed to complete the task. The major advantage of the proposed system is that it can provide visualized images of internal structures of the running aero-engine without physical disturbance, which makes it possible to extract the accurate geometry information. The main idea behind this design is to measure the projection data from various views for reconstructions making use of the rotations of the aero-engine blades, instead of the mechanical rotations in the conventional ICT system. However, due to high speed rotation of the aero-engine blades, the system faces more challenges than conventional ICT systems both in data acquisitions and reconstruction algorithms. The challenges and corresponding solutions are presented in this paper. In conclusion, the proposed ICT system provides a powerful tool for monitoring the running aero-engines.

375

Differing from radiography without lens system, the high-energy proton radiography (PRAD) uses Zumbro lens system to focus the penetrating protons. Since the Zumbro lens system is able to limit the range of multiple Coulomb scattering angles of the protons, the low-energy PRAD with Zumbro lens system is also feasible, although the attenuation of probing protons in the object is negligible. Low-energy PRAD is superior to the high-energy PRAD for diagnosing the objects of small thicknesses. To verify the imaging principle of Zumbro lens system, 11 MeV PRAD experiments were performed at the China Academy of Engineering Physics (CAEP) recently. The experiment results demonstrated that this 11 MeV PRAD was able to radiograph objects of area density less than 2.7×10^-2 g/cm² and the area density discrepancy less than 2.3% could be distinguished.

467

478

Poor mechanical properties of PNIPAAm hydrogels have limited their applications. Nanocomposite hydrogels (NC gels) which incorporate inorganic clay possess high mechanical strength and other desirable properties. In this paper, we report a facile approach to synthesize NC gels using radiation technique. With exfoliated clay sheets acting as crosslinkers, N-isopropylacrylamide monomers are polymerized and crosslinked to form NC gels under γ-irradiation at room temperature. Apart from regular swelling behavior and interesting performance in thermo sensitivity, the radiation synthesized NC gel (RNC gel) has good optical transparency, high strength and flexibility. Through Micro-FTIR, XPS and TG analyses, a particular chemically crosslinked organic/inorganic network was identified in the RNC gel.

525

Hydroxyethylidene diphosphonate (HEDP) was prepared and labeled with rhenium-188. Its lyophilized kit was developed for instant preparing of ¹⁸⁸Re-HEDP. ¹⁸⁸Re-HEDP showed high focile uptake in normal mice (>30% ID/g at carrier co-injection) in BABLC/SPF mice. High quality single photon emission computed tomography (SPECT) image of New Zealand rabbit was obtained at 4 h after intravenous injection of 74 MBq radiotracer. The lyophilized HEDP kit affords the new opportunity for routine clinical application in bone metastases therapy.

356

A method is established for measuring low energy γ-rays dose by using CMOS sensors without any X-/γ-ray converters. Gamma-ray source of ²⁴¹Am and ¹⁵²Eu are used to test the system. Based on gray value, an analysis method is proposed to obtain the γ-ray dose. Cumulative dose is determined by correlating the gray value to the dose readings of standard dosimeters. The relationship between gray value and the cumulative dose of γ-rays are trained by using back propagation neural network with BFGS algorithm. After comparison, it shows that BFGS algorithm trainings are suitable for different γ-ray sources under higher error condition. These indicate the feasibility of measuring low energy γ-ray dose by using common CMOS image sensors.

355

In the RCPI (rod control and position indication) system prototype of the TMSR (Thorium Molten Salt Reactor) project, EPICS (Experimental Physics and Industrial Control System) was adopted as instrumentation and control software platform. According to long time running, high availability and safety for the system, RMT (redundancy monitor task) software package for Input/Output Controller (IOC) redundancy was employed, and the driver for redundancy control was realized. Test shows that the system could achieve IOC redundancy switch-over quickly and ensure the IOC running with long-term stability.

333

Commercial off-the-shelf (COTS) ADCs (analog-to-digital converters) that are radiation-tolerant, high speed, high density and low power will be used in upgrading the LAr (liquid argon) calorimeter front end (FE) trigger readout electronics. Total ionization dose (TID) and single event effect (SEE) of the COTS ADCs should be characterized. In our initial TID test, 17 COTS ADCs from different manufacturers with dynamic range and sampling rate meeting requirements of the FE electronics were checked, and the ADS5272 of Texas Instruments (TI) was the best performer of all. Another interesting feature of ADS5272 is its 6.5 clock cycles latency, which is the shortest of all the 17 candidates. Based on the TID performance, we designed an SEE evaluation system for ADS5272, which allows us to further assess its radiation tolerance. In this paper, we present a detailed design of ADS5272 SEE evaluation system and show the effectiveness of this system while evaluating ADS5272 SEE characteristics in multiple irradiation tests. According to TID and SEE test results, ADS5272 was chosen to be implemented in the full-size LAr Trigger Digitizer Board (LTDB) demonstrator, which will be installed on ATLAS calorimeter during the 2014 Long Shutdown 1 (LS1).

396

The reliability of radiotherapy was evaluated and effective approaches were obtained in order to improve radiotherapy quality by using the Probabilistic Safety Assessment (PSA) method. This study investigated the feasibility of the PSA method being applied to radiotherapy through Image-guided Radiotherapy (IGRT) and chest tumor irradiation. A fault tree has been constructed after analyzing causal relationship of the events. After calculating RiskA, a total inaccuracy radiotherapy probability and the importance of all base events were obtained. The probability of inaccurate radiotherapy was 2.87%. Under the condition that the target delineation was perfectly right, the accuracy of radiotherapy significantly improved. With the calculation without Cone-beam Computed Tomography (CBCT) being corrected before irradiation, the accuracy significantly decreased. The most important events were connected with the human factor. Improving human technical level could enhance radiotherapy quality control efficiently.

357

Peptide GAV-9 is derived from 3 different disease related proteins. The self-assembly of GAV-9 in a water nanofilm attracted much attention recently. We studied how the temperature factor influenced the peptide self-assembly in a water nanofilm and found interesting phenomena: 1) the higher the temperature, the faster the nanofilaments grow; 2) the GAV-9 peptide formed double monolayers in a water nanofilm at 60 ℃, which further supports the hypothesis that the water nanofilm could change the hydrophobicity of mica. We believe these results can help not only the microcontact printing of amyloid peptides, but also a better understanding on how temperature controls the properties of water nanofilm.

431

Molecularly thin water layer, with a hydrogen bonding network different from those in bulk water and ice, has unique properties and is generally involved in many important processes such as wetting, erosion, atmosphere chemical reaction, protein folding and biomolecular interaction. Here, we report a new water layer structure at room temperature, which is found inside nanobubbles by using synchrotron based scanning transmission soft X-ray microscopy (STXM). The three peaks 535.0, 536.8 and 540.9 eV at O K edge inside the nanobubbles show a novel characteristics of very thin water layers, which has never been observed before.

381

This work determined a new M-C code (FLUKA) that can be used to calculate the dosimetric characteristics of seed sources. Dosimetric parameters (dose rate constant, radial dose function, and anisotropy function) of model 6711 ¹²⁵I seed source were calculated with FLUKA. The results were compared to the relative data recommended by AAPM TG43U1: dose rate constant with FLUKA was in agreement with 2.041%; radial dose functions with FLUKA for distances ranging from 0.5 cm to 10 cm, the deviation was less than 5%. Therefore the FLUKA code can be used to calculate the dosimetric characteristics of seed sources.

355

Oxygen control technology is a critical issue for compatibility of candidate structural materials with liquid lead-bismuth eutectic (LBE) in accelerator driven systems. Performances of a self-developed Pt/air sensor and another one from Karlsruher Institute of Technology (KIT) were tested in stagnant oxygen-saturated liquid LBE. Calibrations showed that the trend and values of corrected electromotive force (EMF) of the self-developed sensor, with a bias voltage of 20 mV, were consistent with theoretical results above 425 ℃, and similar results were obtained in cross-calibration test with EMF value of KIT sensor as reference. In stability test at 450 ℃ for 100 hours, the KIT sensor performed better than the self-developed one, which showed signal fluctuations. Both sensors exhibited quick response to temperature variations in the responsiveness test.

551