55936689
A MONITORING SYSTEM FOR CSR POWER SUPPLY
This article elaborated the monitoring system which has applied in the CSR power supply. This system is composed of the hardware and the software. The hardware is composed of PS6040-PXI-18 PXI engine case +PXI-3800 the master controller +PXI-6133 the ADC card. The software uses NI Corporation's LABVIEW to carry on the data demonstration and the analysis. This monitoring system in the CSR debugging, in the acceptance and the running has played the influential role. At the same time, it provided the data for the physical person. This monitoring system has run four years in the CSR. OVERVIEW CSR, a new ion Cooler-Storage-Ring (CSR) project, is the post-acceleration system of the Heavy Ion Research Facility in Lanzhou (HIRFL). Figure 1 show an Overall Layout of HIRFL-CSR. CSR is a multi-purpose CSR system that consists of a main ring (CSRm), an experimental ring (CSRe), and a radioactive beam line (RIBLL II) to connect the two rings. The two existing cyclotrons SFC (K = 69) and SSC (K = 450) of the HIRFL will be used as its injector system. The heavy ion beams with the energy range of 8–30 MeV/u from the HIRFL will be accumulated, cooled and accelerated to the high-energy range of 100–400 MeV/u in the main ring, and then extracted fast to produce RIB or highly charged heavy ions. The secondary beams (RIB or highly charged heavy ions) will be accepted and stored by the experimental ring for many internal-target experiments or high-precision spectroscopy with beam cooling. On the other hand, the beams with the energy range of 100–900 MeV/u will also be extracted from CSRm by using slow extraction or fast extraction for many external-target experiments.
17261464
Black hole to bulge mass correlation in Active Galactic Nuclei: a test for the simple unified formation scheme
A mass correlation of central black holes and their spheroids similar to 0.002 (within a factor of three) is suggested by Hubble Space Telescope (HST) and various ground-based CCD photometries of early type galaxies. The near-IR images of quasar hosts and the emission line measurements of Broad Line Region for bright QSOs present a similar correlation, which supports the speculation of an evolutionary linkage between the early active QSO phase and the central black holes in normal galaxies. On the other hand, recent reverberation mapping of a sample of Seyferts shows a broad distribution of black hole to bulge mass ratio with a mean of similar to 10(-3.5), about one magnitude lower than the value in early type galaxies and bright QSOs. Adopting a simple unified formation scheme for QSOs and Seyferts, we will discuss in this letter the dependence of the black hole to bulge mass ratio in Active Galactic Nuclei (AGNs) on the environmental parameters of the host galaxies. We show a broad distribution of the mass correlation could be due to different velocity dispersion of the accreting gas from different Formation mechanism, and the mass ratio in normal galaxies and bright QSOs is probably a limit case of black hole evolution by merger enhanced accretion close to Eddington limit.
145039581
Contribution of starburst mergers at z ∼ 1 to the strong evolution of infrared and submillimeter deep surveys
Recent far-infrared and submillimetre waveband observations revealed a large number of Ultraluminous Infrared Galaxies (ULIGs) with infrared luminosities >10 L . These sources are proposed to lie at redshifts above one, and in normally interacting systems with very dusty environments. We discussed in a previous paper that a population with a fast evolving infrared burst phase triggered by gas-rich mergers at z ∼ 1 predicted successfully the steep slope of faint IRAS 60 μm source counts within the flux range of 100 mJy ∼ 1 Jy, still leaving the infrared background level at this wavelength compatible with the upper limit from recent high energy TeV γ ray detection of Mrk 501. To extend the model to mid and far infrared wavelengths, we adopt a reasonable template spectral energy distribution typical for nearby-infrared-bright starburst galaxies (Lir <= 10 12 L ), such as Arp 220. We construct the SED for the dusty starburst mergers at z ∼ 1 by a simple dust extinction law and a thermal continuum assumption for the far-infrared emission. Since the radiation process at mid-infrared for these starburst merging systems is still uncertain, we assume it is similar to the MIR continuum of Arp 220, but modify it by the observed flux correlation of ULIGs from IRAS and ISOCAM deep surveys. We show in this paper that the strong evolution of the European Large Area ISO Survey (ELAIS) at 90μm, ISO 170μm and the Submillimeter deep survey at 850μm could be sufficiently accounted for by such an evolutionary scenario, especially the hump of the ISOCAM 15μm source count around 0.4 mJy. From current best fit results, we find that the dust temperature of those extremely bright starburst merging system at z ∼ 1 would be higher than that of Arp 220 for a reconciliation of the multi-wavelength infrared deep surveys. We thus propose that the infrared burst phase of dusty starburst galaxies or AGNs from gas-rich mergers at z ∼ 1 could contribute significantly to the strong evolution of the IRAS 60μm, the ISO 15μm, 90μm, 170μm, as well as the SCUBA 850μm number counts, while being compatible with the current observational limits of the cosmic infrared background and the redshift distributions. The major difference of our current model prediction is that we see a fast convergence of the differential number counts at 60μm below 50 mJy, which is about a factor of two brighter than other model predictions. Future infrared satellites like Astro-F or SIRTF would give strong constraints to the models.
17712450
Cosmic star formation history associated with quasar activity: An approach using the black hole-to-bulge mass correlation
The tight correlation between the masses of central black holes and their host spheroids in nearby galaxies and active galactic nuclei (AGNs) suggests that black hole growth is closely related to their spheroid formation. Based on our previous work regarding such a joint evolutionary scheme and the consequential black hole-to-bulge mass correlation, we use the X-ray luminosity function of AGN and the cosmological evolution rate, which are from ROSAT X-ray surveys, to estimate the cosmic star formation history associated with the black hole growth. By the basic assumption that the major black hole growth occurs during the luminous AGN phase, the luminosity function of AGNs as a function of redshift traces not only the accretion history of the black holes but also the cosmic star formation history of the spheroids. Although the space density of the especially luminous quasars is very low, we show that the total amount of star formation associated with the massive black hole growth is almost the same as that of Lyman break galaxies detected by the current optical deep surveys. We thus argue that the optical deep surveys may miss about half of the net star formation in our universe. This is probably due in part to significant dust extinction, as well as the small field of view of previous optical surveys, which cannot sample such rare events with relatively short timescale. However, the far-infrared emission from the dust heated by ongoing star formation during the black hole growth could sufficiently account for the observed SCUBA number counts and would be the probable dominating energy source of the SCUBA population.
2976540
Infrared–red cores in nearby elliptical galaxies
We present the Spitzer Space Telescope Infrared Array Camera observations for a sample of local elliptical galaxies to study later stages of active galactic nucleus (AGN) activity. A sample of 36 elliptical galaxies is selected from the Palomar spectroscopic survey. We detect nuclear non-stellar infrared emission in nine of them. There is unambiguous evidence of circumnuclear dust in these nine galaxies in their optical images. We also find a remarkable correlation between the infrared excess emission and the nuclear radio/X-ray emission, suggesting that infrared excess emission is tightly related to nuclear activity. The possible origin of infrared excess emission from hot dust heated by the central AGN is supported by the spectral indices of the infrared excess emission.
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.
109363234
Tuning the rf cavity by using a detuning loop
The tuning of the rf cavity with a coupling loop connected to a variable capacitor or an open or shorted coaxial line is described. Two kinds of equivalent circuits are described and some of the calculations of ..delta..f and Q vs capacitance curves are given. At 52 MHz the maximum practical tuning range is about 100 KHz, if the parameters of tuning circuit are chosen properly so that the Q of the accelerating cavity does not decrease too much.
61057086
The BEPC control system upgraded
The upgrade of the BEPC control system has been finished one year ahead of the schedule and new system was put into use in October, 1994. The upgraded system adopts a distribution architecture based on DECnet. The workstations are used as console to replace the old hardware console, the new VAX computers carry out control jobs. Some dedicated adapters have been eliminated. Up to now, the new BEPC control system has been running safely and reliably for five months. The system upgrading is crowned success. What we have been finished is presented in this paper.
123655843
Back-streaming ion emission and beam focusing on high power linear induction accelerator
Ions released from target surfaces by impact of a high intensity and current electron beam can be accelerated and trapped in the beam potential, and further destroy the beam focus. By solving the 2D Poisson equation, we found that the charge neutralization factor of the ions to the beam under space charge limited condition is $1/3$, which is large enough to disrupt the spot size. Therefore, the ion emission at the target in a single-pulse beam/target system must be source limited. Experimental results on the time-resolved beam profile measurement have also proven that. A new focus scheme is proposed in this paper to focus the beam to a small spot size with the existence of back-streaming ions. We found that the focal spot will move upstream as the charge neutralization factor increases. By comparing the theoretical and experimental focal length of the Dragon-I accelerator (20 MeV, 2.5 kA, 60 ns flattop), we found that the average neutralization factor is about 5% in the beam/target system.
122214277
A water Cherenkov calorimeter for long baseline neutrino oscillation experiments
Abstract We propose a water-based large homogeneous calorimeter as the next generation neutrino detector for ν factories and/or conventional ν beams. The Cherenkov light produced in water is sufficient to have good energy resolution, and the pattern recognition is realized by a modular water tank structure. Monte Carlo simulations show that the detector performance is excellent for identifying neutrino CC events while rejecting backgrounds.