122693286
Nuclear effects in the semi-inclusive cross section of high energy neutrino-nucleus interactions
Abstract In high energy neutrino scattering off nuclei, the cross sections σ ( x ) show experimentally a remarkable dependence on the presence or the absence of slow recoil protons. It is found that the effect is explained by the kinematics of slow protons directly produced by diquark fragmentation and the rescattering of leptoproduced nucleons.
15022310
A Deformable Bag Model of Hadrons. I
As a generalization of the MIT spherical bag model, we construct the spheroidal bag model of hadron with an arbitrary eccentricity. This generalization is made by slightly modifying the MIT linear boundary condition: The linear boundary condition is examined in detail. Our model always satisfies two necessary requirements of the MIT bag model --i. e., n-j=O, no quark colour flux leaves the bag, and ijq =0, the scalar density of quark should vanish on the bag surface-- and it reduces to the MIT spherical bag model in the limit of zero-eccentricity. Lagrangian formalism of our model is briefly described. The eigenfrequencies of a single massless quark confined in this spheroidal bag are numer­ ically calculated. We obtain the level-splitting of the excited quark orbits, which is just analogous to the well-known Nilsson's splitting of single particle orbits in deformed nuclei. By using the numerical results of the lowest orbit, the effect of the bag-deformation on the mass of low-lying hadrons is estimated. It is found that, although the spherical bag is stable, tbe quark bag is extremely soft against the quadrupole deformation. Brief discussions are added on the mechanisms which make the spherical bag more stable.
121131573
New Scaling Phenomena in Nuclear Structure Functions
We consider the nuclear mass-number (A) dependence of the nuclear structure functions. We restrict ourselves to a two-component model, in which we assume the existence of an exotic component other than the normal nucleon component in nuclei. We find that there exist scaling phenomena and that the structure function of the exotic component should be independent of A. We also show that the A dependence of the nuclear structure function can be attributed to that of the surface-to-volume ratio which is incorporated in the probability of finding the exotic component in the nucleus.
119311709
A new molecular dynamics calculation and its application to the spectra of light and strange baryons
A new approach based on antisymmetrized molecular dynamics is proposed to correctly take account of the many-body correlations. We applied it to the spectra of low-lying, light and strange baryons. The inclusion of the quark–quark correlation is important to predict the precise spectra, and the semi- relativistic kinematics is also vital to correct the level ordering. The baryon spectra calculated by the present method is as precise as the Faddeev calculation.
10938062
Composite nucleons in scalar and vector mean fields.
We emphasize that the composite structure of the nucleon may play quite an important role in nuclear physics. It is shown that the momentum-dependent repulsive force of second order in the scalar field, which plays an important role in Dirac phenomenology, can be found in the quark-meson coupling (QMC) model, and that the properties of nuclear matter are well described through the quark-scalar density in a nucleon and a self-consistency condition for the scalar field. The difference between theories of pointlike nucleons and composite ones may be seen in the change of the {omega}-meson mass in nuclear matter if the composite nature of the nucleon suppresses contributions from nucleon-antinucleon pair creation.
119162077
The quark-meson coupling model and chiral symmetry
We extend the quark‐meson coupling (QMC) model to incorporate chiral symmetry. The relationship between the QMC model and chiral perturbation theory is also discussed. The nuclear central potential is modified by the effect of internal structure of the nucleon.
14514129
BEAM LOADING EFFECTS IN JHF SYNCHROTRON
Beam loading effects on the rf system of JHF proton synchrotrons have been investigated by both computer simulation and experiment using a low energy electron beam. From the simulation results, it is found that even under the heavy beam loading the beam acceleration becomes stable if applying the beam loading compensation, and the compensation experiment is succeeded on proto-type Magnetic Alloy loaded cavity.
36510813
High pressure rinsing system comparison
High pressure rinsing (HPR) is a key process for the surface preparation of high field superconducting cavities. A portable apparatus for the water jet characterization, based on the transferred momentum between the water jet and a load cell, has been used in different laboratories. This apparatus allows collecting quantitative parameters that characterize the HPR water jet. In this paper, we present a quantitative comparison of the different water jets produced by various nozzles routinely used in different laboratories for the HPR process.
56351344
RF SYSTEMS FOR JHF SYNCHROTRONS
Based on the measurements of the magnetic cores and R&D works, MA(Magnetic Alloy)-loaded cavity will be adopted for the RF cavity of JHF 50 GeV Main Ring and 3 GeV Booster. Because of high stability at large RF amplitude, high gradient of acceleration voltage (>50 kV/m) is available. By a test cavity, 2.5 kV/core has been already achieved in the CW operation using one MA core of 2.5 cm thickness. For the pulse operation, 5.5 kV/core has been obtained. Another advantage is that the system does not require the tuning system because of the cavity band width is wide enough to cover the RF frequency. A stability analysis shows that the RF system without the tuning loop has wider stable region than high Q cavity system with the loop. A multi-particle simulation shows that the RF system is also stable for the periodic transient and the RF bucket distortion. However, the distortion should be corrected when the Q value of the cavity is low (Q<2).
55126118
ACHIEVEMENT OF 40 MV/m ACCELERATING FIELD IN L-BAND SCC AT KEK
Two superconducting cavities developed at KEK showed good cavity performances; Eacc = ~40 MV/m. The 1st cavity achieved 40 MV/m adopted 1400 °C heat treatment at half-cell and 120 μ EP at single cell state. On the other hand, at the 2nd cavity no 1400 °C heat treatment was adopted and 30μm tumbling + 30μm EP were applied for surface polishing. In the rinsing procedures of both cavity, ultra-pure water was not used at all for initial 40 MV/m achievement of each cavities; only pure water was used. The niobium sheet of RRR = 200 were used for both cavities. Some degradation of Q0 were observed in Q-E curve probably due to thermal heating. Peculiar temperature dependence (at 1.6 -1.8 K) of cavity performance was observed at 2nd cavity while not observed in the 1st cavity. An analysis of the cavity performances at maximum field may indicate the thermal quench but unusual one. To the 1st cavity, several attempts have been tried repeatedly for intending further improvement and for checking preparation systems.
55112672
Improvement of cavity performance by electropolishing in the 1.3 GHz Nb superconducting cavities
A steep drop of the cavity quality factor (Q/sub 0/) at high electric field has been observed frequently in chemically-polished and high-pressure-rinsed Saclay cavities, even in the absence of field emission. Three single-cell cavities from Saclay were tested at KEK following electropolishing and high pressure rinsing. This treatment eliminated the steep Q/sub 0/ drop, the quench field increased to an accelerating gradient of more than 30 MV/m with a quality factor above 2/spl times/10/sup 10/. No dependence of the quench field on the niobium RRR was observed between RRR=200 and 320 in electropolished cavities.