120104096
High power CW linac in PNC
Power Reactor and Nuclear Fuel Development Corporation (PNC) is developing a high power electron linac for various applications. The electron beam is accelerated in CW operation to get maximum beam current of 100 mA and energy of 10 MeV. Crucial components such as a high power L-band klystron and a high power traveling wave resonant ring(TWRR) accelerator guides were designed and manufactured and their performance were examined. These design and results from the recent high power RF tests were described in this paper.<<ETX>>
95672151
Studies of neutron emission from relativistic nuclear interactions
Abstract Studies were carried out on the yields and spatial distributions of secondary neutrons produced in the relativistic nuclear interactions of 1.5 GeV to 14.4 GeV projectiles p, d and α-particles with targets Pb and U/Pb. CR-39 track detectors were used to measure the neutrons. It shows that: (1) Secondary neutrons are produced in the whole length of Pb or U targets having a thickness of 20 cm. The neutron intensities produced by proton bombardments are reduced along the proton beam direction in the targets. The higher the energy of protons, the lower the reduction rate of the neutrons. The reduction rate of neutrons in U target is higher than in Pb target for the same energy of protons. (2) The radial intensities of neutrons decrease as the distance increases from the target central line. (3) The neutron yield in U target by proton bombardments is ∼55% higher than in Pb target. (4) The ratio of neutron yield by 14.4 GeV α to 7.3 GeV d bombardment in Pb target is 1.74 ± 0.20.
91211418
Further evidences for enhanced nuclear cross-sections observed in 44 GeV carbon ion interactions with copper
1531622
A Monitor Having Lots of Functions for a Linac with Feedback
In our 20 Mev electron linear accelerator with feedback we use a detector in the feedback loop to observe a microwave envelope which includes a lot of information. Under the accelerator operating condition from the micro wave envelope we can monitor the frequency, power, phase and beam loading and calculate the attenuation constant, group velocity, filling time and the field multiplication factor. We can also observe some unstable phenomena.
97825201
Investigation of neutron spectrum emitted from 44 GeV 12C+Cu interactions with nuclear emulsion
Abstract The Energy Spectrum of fast neutrons produced in 44 GeV 12 C+Cu interactions has been measured and analysed with nuclear emulsion of 8 cm in length, 2.2 cm in width and 400 μm in thickness made in China Institute of Atomic Energy, Beijing, China. The irradiation of the emulsion was carried out at the accelerator SYNCHROPHASOTRON of the Joint Institute for Nuclear Research, Dubna, Russia. The neutron spectrum was obtained through measuring the recoil protons in emulsion and the track parameters of α particles from interactions of 12 C(n,n′)3α in emulsion. The experimental neutron spectrum was compared with the results of a Monte-Carlo calculation, which shows that the shapes of both neutron spectra are identical within the limits of their statistical accuracy.
40320436
Microwave Matching and Tuning on the 20-MeV Medical Electron Linac with Feedback of RF Power
In the linac with feedback (or with the resonator) the reflection affects the energy gain of the electron and the performance of the accelerator. By means of the theory of the traveling wave resonator, the field multiplication factor and the reflection coefficients inside and outside the feedback ring are calculated. The bands of the linacs without and with feedback are measured. In order to achieve a desirable band, in front of the load (i.e. outside the feedback ring) a matching iris is added. After the linac with feedback has been matched, the band is given.
119260012
Multiwavelength properties of a new Geminga-like pulsar: PSR J2021+4026
In this paper, we report on a detailed investigation of the multiwavelength properties of a newly detected gamma-ray pulsar, PSR J2021+4026, in both observational and theoretical aspects. We first identify an X-ray source in the XMM-Newton serendipitous source catalogue, 2XMM J202131.0+402645, located within the 95 per cent confidence circle of PSR J2021+4026. With an archival Chandra observation, this identification provides an X-ray position with arcsecond accuracy which is helpful in facilitating further investigations. Searching for the pulsed radio emission at the position of 2XMM J202131.0+402645 with a 25-m telescope at Urumqi Astronomical Observatory resulted in null detection and places an upper limit of 0.1 mJy for any pulsed signal at 18 cm. Together with the emission properties in X-ray and gamma-ray, the radio quietness suggests PSR J2021+4026 to be another member of Geminga-like pulsars. In the radio sky survey data, extended emission features have been identified in the gamma-ray error circle of PSR J2021+4026. We have also re-analysed the gamma-ray data collected by Fermi's Large Area Telescope. We found that the X-ray position of 2XMM J202131.0+402645 is consistent with that of the optimal gamma-ray timing solution. We have further modelled the results in the context of the outer gap model, which provides us with constraints for the pulsar emission geometry such as the magnetic inclination angle and the viewing angle. We have also discussed the possibility of whether PSR J2021+4026 has any physical association with the supernova remnant G78.2+2.1 (gamma-Cygni).
122216623
Measuring accelerating universe with high-redshift GRBs data and other cosmological probes
A kinematical model (a parameterized deceleration parameter) and a dynamical model (a parameterized equation of state for dark energy) are constrained from the current observational data including the high-redshift Gamma-Ray Bursts (GRBs) data with a redshift range from 1.4 to 9. We obtain the stringent constraint on the values of current deceleration parameter q0, current jerk parameter j0, current equation of state for dark energy w0de and transition redshift zT. In addition, we compare the difference of the constraint results between the kinematical and the dynamical scenarios.
111171338
DEVELOPMENT OF RADIO FREQUENCY GUNS AT NSRRC
Technologies for rf gun-based high brightness injector are being developed at NSRRC. An X-band photo-cathode rf gun has been constructed and operated successfully for coherent electromagnetic radiation research at U.C. Davis. Recent measurement of a 1.5-2 MeV beam from this gun with bunch charge at 25 pC showed that it has a normalized emittance at 1.65 mm-mrad. As a successive project, a 100 MeV electron beam injector system with a thermionic rf gun and a photo-cathode rf gun that share the same 2998 MHz rf linac is being designed as the pre-injector of the TPS (Taiwan Photon Source) booster as well as beam injector for novel light source research. For evaluation purposes, a prototype thermionic rf gun system is now under construction at NSRRC with the existing 2856 MHz high power microwave system as the driver source.
55509875
A LOW COST AND HIGH EFFICIENCT FACILITY FOR REMOVAL OF SO2 AND NOx IN THE FLUE GAS FROM COAL FIRE POWER PLANT
The emission of toxic gas, sulfur oxides and nitrogen oxides has become serious issue in the world. A review of EB method to remove the SOx and NOx in flue gas from coal-fired power plants was described in this paper. A design of an electron curtain accelerator of 600 keV was given, and a facility for purification of flue gas from coal combustion power plant of 10MW was described here.
119093990
Observational Constraints on Dark Energy and Cosmic Curvature
Current observational bounds on dark energy depend on our assumptions about the curvature of the universe. We present a simple and efficient method for incorporating constraints from cosmic microwave background (CMB) anisotropy data and use it to derive constraints on cosmic curvature and dark energy density as a free function of cosmic time using current CMB, Type Ia supernova (SN Ia), and baryon acoustic oscillation data. We show that there are two CMB shift parameters, R{identical_to}{radical}({omega}{sub m}H{sub 0}{sup 2})r(z{sub CMB}) (the scaled distance to recombination) and l{sub a}{identical_to}{pi}r(z{sub CMB})/r{sub s}(z{sub CMB}) (the angular scale of the sound horizon at recombination), with measured values that are nearly uncorrelated with each other. Allowing nonzero cosmic curvature, the three-year WMAP (Wilkinson Microwave Anisotropy Probe) data give R=1.71{+-}0.03, l{sub a}=302.5{+-}1.2, and {omega}{sub b}h{sup 2}=0.02173{+-}0.00082, independent of the dark energy model. The corresponding bounds for a flat universe are R=1.70{+-}0.03, l{sub a}=302.2{+-}1.2, and {omega}{sub b}h{sup 2}=0.022{+-}0.00082. We give the covariance matrix of (R,l{sub a},{omega}{sub b}h{sup 2}) from the three-year WMAP data. We find that (R,l{sub a},{omega}{sub b}h{sup 2}) provide an efficient and intuitive summary of CMB data as far as dark energy constraints are concerned. Assuming the Hubble Space Telescope (HST) prior of H{sub 0}=72{+-}8more » (km/s) Mpc{sup -1}, using 182 SNe Ia (from the HST/GOODS program, the first year Supernova Legacy Survey, and nearby SN Ia surveys), (R,l{sub a},{omega}{sub b}h{sup 2}) from WMAP three-year data, and SDSS (Sloan Digital Sky Survey) measurement of the baryon acoustic oscillation scale, we find that dark energy density is consistent with a constant in cosmic time, with marginal deviations from a cosmological constant that may reflect current systematic uncertainties or true evolution in dark energy. A flat universe is allowed by current data: {omega}{sub k}=-0.006{sub -0.012-0.025}{sup +0.013+0.025} for assuming that the dark energy equation of state w{sub X}(z) is constant, and {omega}{sub k}=-0.002{sub -0.018-0.032}{sup +0.018+0.041} for w{sub X}(z)=w{sub 0}+w{sub a}(1-a) (68% and 95% confidence levels). The bounds on cosmic curvature are less stringent if dark energy density is allowed to be a free function of cosmic time, and are also dependent on the assumption about the early time property of dark energy. We demonstrate this by studying two examples. Significant improvement in dark energy and cosmic curvature constraints is expected as a result of future dark energy and CMB experiments.« less