Nearly transform-limited optical pulse from a passively mode-locked laser diode

An optical ultra-short pulse train with a duration of 2.9 ps was successfully generated from a passively mode-locked laser diode. The time-bandwidth product was 0.43, and it was very close to the transform-limited value of a Gaussian waveform. The highest peak power of 10 mW in an InP-based passively mode-locked laser has been achieved. The laser is promisng as an optical source for an ultra-high-speed bit rate transmission system, especially for the optical time division multiplexing (OTDM) system.     

Bifurcations and observation of strange attractor in He-Ne lasers

We report the experimental observation of deterministic chaos in an He-Ne laserat 0.6328μm by varying the discharge current.Strange attractor of laser system in the recon-structed phase-space picture has been obtained.The mechanism of the phenomena was dis-cussed.     

Effect of deuteron density distribution on the deduction of screening potential from the D（d,p）T reaction in Be metals

The D(d,p)T reaction in Be metal environments has been measured to investigate the electron screening effect in metals in an energy region of from 5.5 keV to 10 keV in a center of mass system (CMS) at a temperature of 121 K. The depth distribution of deuteron density in Be metals has an impact on the observed reaction yields. A model of deuteron density distribution in metal has been proposed to obtain the original yields. A screening energy of (116±46) eV has been obtained with the assumed deuteron density distribution model.     

Electric field simulation and measurement of a pulse line ion accelerator

An oil dielectric helical pulse line to demonstrate the principles of a Pulse Line Ion Accelerator (PLIA) has been designed and fabricated. The simulation of the axial electric field of an accelerator with CST code has been completed and the simulation results show complete agreement with the theoretical calculations. To fully understand the real value of the electric field excited from the helical line in PLIA, an optical electric integrated electric field measurement system was adopted. The measurement result shows that the real magnitude of axial electric field is smaller than that calculated, probably due to the actual pitch of the resister column which is much less than that of helix.     

FP cavity and FBG cascaded optical fiber temperature and pressure sensor

A fiber Bragg grating(FBG) and Fabry–Perot(FP) cavity cascaded fiber sensing system was manufactured for temperature and pressure sensing. Temperature sensing as high as 175°C was performed by an FBG for the linear variation of an FBG wavelength with temperature. After the temperature was sensed, the demodulation system can find the original FP cavity length and its pressure and cavity length correlation coefficient; thus, the ambient pressure would be calculated. The sensing pressure can be as high as 100 MPa with a repeatability of 1/10,000 and high stability. This kind of fiber sensor has been used in the Shengli Oil Field.     

Design of the thermal neutron detection system for CJPL-Ⅱ

A low background thermal neutron flux detection system has been designed to measure the ambient thermal neutron flux of the second phase of the China Jinping Underground Laboratory(CJPL-Ⅱ),right after completion of the rock bolting work.A ~3He proportional counter tube combined with an identical ~4He proportional counter tube was employed as the thermal neutron detector,which has been optimised in energy resolution,wall effect and radioactivity of construction materials for low background performance.The readout electronics were specially designed for long-term stable operation and easy maintenance in an underground laboratory under construction.The system was installed in Lab Hall No.3 of CJPL-Ⅱ and accumulated data for about 80 days.The ambient thermal neutron flux was determined under the assumption that the neutron field is fully thermalized,uniform and isotropic at the measurement position.     

ANL的2Q-LEBT装置的进展报告

The concept for a 2 charge state injector for a"RIA type"accelerator has been presented.Progress toward an operational prototype 2Q-LEBT system at Argonne National Laboratory(ANL)is under way. The existing BIE 100 all permanent magnet ECR has been placed on a high voltage platform capable of a combined>100kV with q/m separation at ground level.Remote control of the devices on the platform has been implemented.Other components of the facility are currently being tested.The components of an achromatic bending system are currently being procured.This paper will present recent work at the facility as well as preliminary development of solid materials using the BIE 100.     

Performance evaluation of BPM system in SSRF using PCA method

The beam position monitor (BPM) system is of most importance in a light source. The capability of the BPM depends on the resolution of the system. The traditional standard deviation on the raw data method merely gives the upper limit of the resolution. Principal component analysis (PCA) had been introduced in the accelerator physics and it could be used to get rid of the actual signals. Beam related information was extracted before the evaluation of the BPM performance. A series of studies had been made in the Shanghai Synchrotron Radiation Facility (SSRF) and PCA was proved to be an effective and robust method in the performance evaluations of our BPM system.     

R&D of an LLRF control system for a 162.5 MHz radio frequency system

This paper describes a low level radio frequency control system that was developed by the Institute of Modern Physics Chinese Academy of Sciences, and will be used in Injector of the China-ADS project. The LLRF control system consists of an RF modulated front end, fast analog-to-digital converter (ADC) modules, and a digital signal processing board based on a field programmable gate array. The system has been tested on a room temperature cavity with 12-hr, and the results illustrate that the stability of amplitude and phase achieved ±0.32% and ±0.35 degrees, respectively.     

Simulation of ion beam extraction and focusing system

The characteristics of ion beam extraction and focused to a volume as small as possible were investigated with the aid of computer code SIMION 3D version 7. This has been used to evaluate the extraction characteristics (accel-decel system) to generate an ion beam with low beam emittance and high brightness. The simulation process can provide a good study for optimizing the extraction and focusing system of the ion beam without any losses and transported to the required target. Also, a study of a simulation model for the extraction system of the ion source was used to describe the possible plasma boundary curvatures during the ion extraction that may be affected by the change in an extraction potential with a constant plasma density meniscus.     

A novel radiant source for infrared calibration by using a grooved surface

A radiant source with a large aperture at 5-95 ℃ in the wavelength bands of 8-12μm for calibrating infrared imaging systems has been designed. The effective emissivity of its flat bottom with concentric V-grooves was evaluated by the Monte-Carlo method whose correctness was tested and accuracy was discussed. The structure of the source was completed by incorporating the simulation results with the blackbody cavity effect. The source was certificated via an optical measurement system. The source can provide a consistent radiant flux with temperature uniformity of ±0.1 ℃ over an area of diameter of φ80 mm.     

System-Size induced Coherence Resonance in Coupled Minimal Cytosolic Ca^2＋ Oscillation Models

We have investigated the collective behaviour of an array of coupled minimal cytosotic Ca^2＋ oscillation models by numerical methods, taking into account the external noise resulting from the random extracellular stimulation. It is found that the system size, i.e. the number of minimal cytosolic Ca^2＋ oscillation models, has an optimal value, at which the system collective dynamics shows the best performance. The effect of the coupling strength has also been studied. Such a phenomenon of system-size resonance has been found for different coupling strengths, but the optimal system size increases when the coupling strength increases.     

Attenuation length measurements of a liquid scintillator with LabVIEW and reliability evaluation of the device

An attenuation length measurement device was constructed using an oscilloscope and LabVIEW for signal acquisition and processing. The performance of the device has been tested in a variety of ways. The test results show that the set-up has a good stability and high precision (sigma/mean reached 0.4 percent). Besides, the accuracy of the measurement system will decrease by about 17 percent if a filter is used. The attenuation length of a gadolinium-loaded liquid scintillator (Gd-LS) was measured as 15.10±0.35 m where Gd-LS was heavily used in the Daya Bay Neutrino Experiment. In addition, one method based on the Beer-Lambert law was proposed to investigate the reliability of the measurement device, the R-square reached 0.9995. Moreover, three purification methods for Linear Alkyl Benzene (LAB) production were compared in the experiment.     

A novel radiant source for infrared calibration by using a grooved surface

A radiant source with a large aperture at 5-95℃ in the wavelength bands of 8-12 μm for calibrating infrared imaging systems has been designed. The effective emissivity of its flat bottom with concentric V-grooves was evaluated by the Monte-Carlo method whose correctness was tested and accuracy was discussed. The structure of the source was completed by incorporating the simulation results with the blackbody cavity effect. The source was certificated via an optical measurement system. The source can provide a consistent radiant flux with temperature uniformity of ±0.1 ℃ over an area of diameter of φ80 mm.     

Accuracy Measurements of the CAS-LIBB Single-Particle Microbeam for Single Cell Irradiation

A single-particle microbeam facility has been constructed at the Laboratory of Ion Beam Bioengineering (LIBB),Chinese Academy of Sciences. The system is designed to deliver the defined number of hydrogen ions, covering a range of energy from 1.0 to 3.5 MeV, into an area smaller than the nuclei of individual living cells. Accuracy of the particle detection system and the cell targeting system in the facility has been assessed using CR39 (nuclear track detector) for 2.3 MeV protons. The results demonstrate that the particle detection efficiency is above 98%,and the overall targeting accuracy of the microbeam is limited within 3μm for more than 90% hits.     

Investigation on the scattering effect of ceramic Nd:YAG

This paper investigates the scattering effect of domestic 0.5 at{\%} ceramic Nd:YAG. An effective method has been utilized to measure the scattering and absorption coefficients. An end-pumped continuous wave (CW) Nd:YAG ceramic laser was also demonstrated. A maximum output power of 6.7~W at 1064~nm was obtained at an 808-nm pump power of 32.9~W. Conversion efficiency and slope efficiency have been achieved. This indicates that scattering has an important effect on the optical performance of ceramic Nd:YAG.     

A STUDY OF THE FS-PDMP SYSTEM

A signal detection system,which consists of a Frequency-Stepping signal source and a corre-sponding Post-Detected-Matching-Processor,has been studied both theoretically and experimentally.The characteristic function determining the detection performance of the FS-PDMP system is derivedand a set of equipment,which can generate and process an eight-unit long signal with an arbitraryFS mode,has been made for the experimental studies.Some primary results are reported and theyare in conformity with the theoretical analysis.     

Specification and Simulation of the ALICE Trigger and DAQ System

The ALICE Trigger and Data Acquisition (TRG/DAQ) System is required to support an aggregate event building bandwidth of up to 4 GByte/s and a storage capability of up to 1.25 GByte/s to mass storage.The system has been decomposed in a set of hardware and software components and prototypes of these components are being developed.It is necessary to verity the system design,its capability to reach the expected behavior and the target performances,discover possible bottlenecks and ways to correct for them,and explore alternative algorithms and new architectures.To achieve this the complete TRG/DAQ system has been formally specified.and the verification of the expected behavior has been performed through the execution of the specification,Two tools were used for this.Foresight,and Ptolemy.     

First experimental research in low energy proton radiography

Proton radiography is a new scatheless diagnostic tool providing a potential development direction for advanced hydrotesting.Recently a low energy proton radiography system has been developed at the Chinese Academy of Engineering Phyiscs(CAEP).This system has been designed to use an 11 MeV proton beam to radiograph thin static objects.This system consists of a proton cyclotron coupled to an imaging beamline,which is the first domestic beamline dedicated to proton radiography experiments.Via some demonstration experiments,the radiography system is confirmed to provide clear pictures with spatial resolution～100μm within 40 mm field-of-view.