122612139
Energy and fluence determination of fast neutrons from 44 GeV 12C + Cu interactions by CR-39 detector stack
Abstract Copious amounts of fast neutrons are produced in relativistic heavy ion interactions, which bring about information on the mechanisms of relativistic heavy ion interactions and could constitute considerable radiation hazard. In order to determine their energy and yield, we have detected with a CR-39 detector stack neutrons produced in 44 GeV 12 C + Cu interactions at the SYNCHROPHASOTRON, Joint Institute for Nuclear Research (JINR), Dubna, USSR and the neutrons from 400 keV d + T reactions at the Cockroft-Walton, China Institute of Atomic Energy, Beijing, China, for comparison.
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.
91211418
Further evidences for enhanced nuclear cross-sections observed in 44 GeV carbon ion interactions with copper
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.
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.
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.
122576647
On muon production and other leakage aspects of pion absorption in a lead/scintillating-fiber calorimeter
Abstract We report on an experimental study of longitudinal leakage phenomena in hadronic shower development. Pions in the energy range of 10–150 GeV were sent into a lead/scintillating-fiber calorimeter with a thickness of 9.6 nuclear interaction lengths. The average fraction of the energy leaking out at the back of this calorimeter ranges from 0.04% at 10 GeV to 0.4% at 150 GeV. This leakage has a very small effect on the hadronic energy resolution. We measured the probability of the creation of escaping muons in the shower development process. This probability ranges from 0.2% at 10 GeV to 2.1% at 150 GeV. Assuming that these muons are produced from π- or K-decay, we find an exponentially decaying muon spectrum with a typical momentum of 2.8 GeV/ c , at 80 GeV incident energy. Also the rates at which hadrons and soft neutrons escape from the calorimeter are measured. Within the acceptance of the leakage calorimeter, neutrons are observed about 10 times as often as muons. Escaping hadrons dominate muons for shower energies above 20 GeV. The experiments were performed at CERN in the framework of the LAA project.
119624505
Non-Bunch-Davies statistical anisotropies
We introduce a generic mechanism that can extend the effects of relic anisotropies at the beginning of inflation to relatively much shorter scales in density perturbations. This is induced by non-Bunch-Davies states of the quantum fluctuations, and can show up in the non-oscillatory components of the density perturbations. This mechanism works for general forms of anisotropies, and, to illustrate it, we use an example of relic vector field. The detailed scale-dependence of these anisotropies can be used to probe the initial quantum state of our universe.
126182293
Evidence of psi(3770) nonD anti-D decay to J / psi pi+ pi-
118426546
Transverse-Momentum Resummation for Gauge Boson Pair Production at the Hadron Collider
We perform the transverse-momentum resummation for $W^{+}W^{-}$, $ZZ$, and $W^{\pm}Z$ pair productions at the next-to-next-to-leading logarithmic accuracy using soft-collinear effective theory for $\sqrt{S}=8 \text{TeV}$ and $\sqrt{S}=14 \text{TeV}$ at the LHC, respectively. Especially, this is the first calculation of $W^{\pm}Z$ transverse-momentum resummation. We also include the non-perturbative effects and discussions on the PDF uncertainties. Comparing with the next-to-leading logarithmic results, the next-to-next-to-leading logarithmic resummation can reduce the dependence of the transverse-momentum distribution on the factorization scales significantly. Finally, we find that our numerical results are consistent with data measured by CMS collaboration for the $ZZ$ production, which have been only reported by the LHC experiments for the unfolded transverse-momentum distribution of the gauge boson pair production so far, within theoretical and experimental uncertainties.
118389996
Neutron–gamma discrimination of CsI(Na) crystals for dark matter searches
Abstract The luminescent properties of CsI(Na) crystals are studied in this report. Using a TDS3054C oscilloscope with a sampling frequency of 5 GS/s, we find out that nuclear recoil signals are dominated by a very fast light pulse with a decay time of ∼20 ns, while γ-ray signals have a decay time of ∼600 ns. The study of n / γ separation shows that the rejection factor can reach an order of 10 −7 with a signal efficiency of more than 80% at an equivalent electron recoil energy of 20 keV or more, and the quality factors are ∼10 times smaller than that for CsI(Tl) crystals in the corresponding energy region. It is suggested that the wavelength of nuclear recoil and γ-ray signals is also different. Such a property makes CsI(Na) an ideal candidate for dark matter searches.