Search Results (15 total)

A compact proton synchrotron using combined function magnets is proposed to help realize the wider availability of charged particle cancer therapy facilities. This combined function magnet was designed with the help of three-dimensional magnetic field calculations to take account of a realistic fringe and the interference among the magnetic poles. An evaluation scheme for tune values based on particle tracking was developed to improve the magnet design. To verify the magnet design, a model magnet was fabricated and measured. In order to achieve a tune value evaluation from the measured magnetic field, schemes for accurate field mapping and field interpolation were developed. From the tune value evaluation of the measured magnetic field, it was thought that the performance of the model magnet was good enough to construct a synchrotron. In this paper, we report details of the design and the evaluation scheme for the combined function magnet and the results of the field measurements of the model magnet.

Secondary-ion yields have been measured for Si and SiO₂ targets bombarded by C, Si, Ge, and Ag projectiles over an energy range beween 0.4 and 10 MeV, where the atomic-collision process changes from a nuclear to an electronic one. Obtained yields of secondary Si^q+ (q=1,2,3,4) ions for the C projectiles are generally decreasing functions of incident energy. On the other hand, the yields for Ag increase with increasing energy except for Si⁺. The possibility of multiple-charged recoil-ion production through the simultaneous process of ionization and recoil caused by the projectiles is discussed on the basis of an independent-electron model, which describes multiple ionization of atoms by energetic heavy-ion impact.

As was shown for the first time by Fujikawa, the anomaly is fundamentally a variation of the functional integral measure under transformation. Fujikawa’s original prescription of 1979 for the variation of the integral measure looks to be at first sight an artifact. In this paper we will show that it is not and that it is fully equivalent to the authentic field-theoretical treatment for a two-point function. To do this we first examine various ways of solving the factor A(x) in Fujikawa’s expression for the functional integral measure. We define the anomaly as A(x)-A_f(x), where A_f(x) is the Fujikawa factor for the free field. We propose a regulator which leads to a finite result for any anomaly. We show that A(x) can be defined in terms of the proper time through a splitting procedure. The original Fujikawa prescription for A(x) is shown to be closely related to the proper-time description of the anomaly, initiated by Schwinger. Its equivalence to the authentic field-theoretical treatment is proven as a consequence of these investigations. The ζ-functional regularization for A(x) is also examined. We examine the way to deduce the anomaly from the effective potential by adopting the φ⁴ model as an example. Comparison of the path-integral prescription with this procedure enables one to clarify the nature of divergence appearing in the original Fujikawa form of A(x). The renormalization-group equation for the effective potential is solved exactly to obtain the precise form of the β function in terms of which we reexpress the result obtained earlier for A(x). Finally we discuss the physical significance of the renormalization-group equation for the case of broken symmetry.

The Lorentz transformation properties of a spherical extended object in 3 + 1 dimensions and a nonspherical extended object in 2 + 1 dimensions are investigated. In the latter case there appear new sets of quantum operators which cause the rotational fluctuation. Also, for the translational fluctuation, the classical quantum position operators have to be replaced by relativistic operators.

We examine the implications of space-time symmetries for quantum field theories with extended objects. It is shown that the existence of the quantum coordinate (collective coordinate) q→ is a direct consequence of the canonical formulation of translational invariance. In 1 + 1 dimensions, Lorentz invariance fixes uniquely the structure of the theory in the no-particle sector. If the tree approximation is used, the structure of the one-particle sector is also uniquely determined. Finally, the techniques developed in this paper allow us to deduce that nonspherically symmetric objects in three dimensions require additional quantum coordinates besides q→.

We calculate the masses of the decuplet and the octet baryons by using a spin- and SU (3)-spin-dependent quark-quark force. We compare it with the required quark-antiquark force used in a previous paper in order to explain the mass splitting of the P and the V nonet mesons. The result is consistent with the assumption that these two forces are related to each other by charge conjugation. We further observe that the ratio of radial integrals for quark-quark and quark-antiquark symmetry-breaking forces is the same as that for the symmetric forces, if quarks are very heavy.

We introduce a kind of self-charge-conjugate meson multiplets assuming the SU(3) functions of pseudoscalar and vector mesons to be the products of two triplet SU(3) functions. Further, we define the charge-conjugation property for the operator, frequently denoted by H₃, so that each particle and its antiparticle have the same mass. Then it is shown that we can introduce a linear mass-breaking operator for the nonet mesons. It is found that this linear mass-breaking operator mixes the singlet with the T=0, S=0 member of the octet. We illustrate this by analyzing the masses of pseudoscalar and vector mesons. In this analysis a quadratic mass-breaking operator and the Casimir operator are introduced in addition to the linear mass-breaking operator in order to represent all possible independent vector operators and all possible independent invariant operators.

It is shown that the magnetic moment of nuclei can be explained by a refined j-j coupling shell model, where neutron and proton shells are treated simultaneously, using the isotopic spin variable. The experimental moments agree well with the calculated ones for those states which have definite isotopic spin multiplicity. It is shown that a nuclear force caused by a neutral or symmetric meson is consistent with our results, but one caused by a charged meson is excluded.