181. Threshold Behaviour of Meson-Nucleon-S - F. Kleefeld
A new method for the determination of the spin-1/2-3/2-mixing angle and the range parameter of the quarkmodel wavefunction of the resonance S Gamma 11 (1535) is presented. The method ist based on a quantitative calculation of the total cross section of pp ! ppj at threshold. The quantitative on-shell treatment of ISI and FSI is discussed. INTRODUCTION Nearly all calculations for the determination of mixing angles between different spincomponents of baryon wavefunctions are based on spectroscopic models. Beside their advantages these models also contain some problems which are not dissolved yet. The goal of the presented work is an independent way of the determination of mixing angles and range parameters in...

182. Multifragmentation in Relativistic Heavy Ion Reactions - W. Trautmann
Multifragmentation is the dominant decay mode of heavy nuclear systems with excitation energies in the vicinity of their binding energies. It explores the partition space associated with the number of nucleonic constituents and it is characterized by a multiple production of nuclear fragments with intermediate mass. Reactions at relativistic bombarding energies, exceeding several hundreds of MeV per nucleon, have been found very efficient in creating such highly excited systems. Peripheral collisions of heavy symmetric systems or more central collisions of mass asymmetric systems produce spectator nuclei with properties indicating a high degree of equilibration. The observed decay patterns are well described by statistical multifragmentation models. The present experimental and...

183. Observations of the supernova remnants Cas-A and Tycho with the HEGRA stereoscopic IACT system - G. P Uhlhofer,C. A. Wiedner,For The Hegra Collaboration
Recently, young supernova remnants (SNR) from type Ia Supernovae (SNe) have become targets of interest for TeV gamma-ray astronomy. This prompted the HEGRA collaboration to extensively observe Tycho's SNR in 1997 and 1998 with its stereoscopic IACT system. The HEGRA IACT system was also used to observe the young SNR Cas-A. Although considered to be the result of a SN type Ib, the detected strong nonthermal X-ray emission makes this SNR a promising candidate for TeV gamma-ray emission. Given the spatial resolution of the system, both sources are still nearly pointlike. Therefore, the data samples yield an emission sensitivity close to a few percent of the...

184. Observations of the supernova remnants Cas-A and Tycho with the HEGRA stereoscopic IACT system - G. P Uhlhofer,H. V Olk,C. A. Wiedner
Recently, young supernova remnants (SNR) from type Ia Supernovae (SNe) have become targets of interest for TeV gamma-ray astronomy. This prompted the HEGRA collaboration to extensively observe Tycho's SNR in 1997 and 1998 with its stereoscopic IACT system. The HEGRA IACT system was also used to observe the young SNR Cas-A. Although considered to be the result of a SN type Ib, the detected strong nonthermal X-ray emission makes this SNR a promising candidate for TeV gamma-ray emission. Given the 0:1 ffi spatial resolution of the system, both sources are still nearly pointlike. Therefore, the data samples yield an emission sensitivity close to a few percent of the...

185. Search for solar neutrons using NM-64 equipment - Martinic, N. J.; Reguerin, A.; Palenque, E.; Taquichiri, M. A.; Wada, M.; Inoue, A.; Takahashi, K.
Two years (1980 to 1982) neutron monitor data from the Chacaltaya (geographic coordinates: N16.32 deg W68. 15 deg; cutoff rigidity: 13.1 GV; altitude: 5,300 m a.s.l.) station has been scanned; the sampling time of the 12NM-64 neutron monitor is 5 min. The nucleonic component increases have been correlated with 66 hard X-, gamma rays satellite data from solar origin, as reported by several groups. Typical neutron monitor time profiles of the events are presented. Chree-analysis was performed discriminating the events according to its solar coordinates. Ground data from solar limb locii are more enhanced at the time of the onset...

186. The effect of convection on the propagation of relativistic galactic electrons - Lerche, I.; Schlickeiser, R.
The paper presents exact analytical solutions which describe steady-state transport of relativistic electrons subject to diffusion, convection, and radiation losses. The diffusion coefficient is spatially and energy dependent; the bulk convection velocity is considered to be constant and directed outward from the galactic plane. The electron spectral behavior with respect to galactic height and energy indicates that convection provides a 'break' in the steady-state energy spectrum without recourse to distribution of sources. Radio observations of NGC 891 and NGC 4631 galaxies can be used to estimate their diffusion coefficient and its energy dependence. Application of analytical solutions to our Galaxy...

187. Significance of medium-energy gamma-ray astronomy in the study of cosmic rays - Fichtel, C. E.; Kniffen, D. A.; Thompson, D. J.; Bignami, G. F.; Cheung, C. Y.
The paper examines the medium-energy (about 10-30 MeV) galactic gamma-ray radiation from primary and secondary electrons and calculates the expected gamma-ray distribution for the specific model of Bignami et al. (1975) on the assumption that the cosmic rays are correlated with the matter on the scale of galactic arms. The energy spectrum typical of regions near the galactic center indicates a dramatic shift from a predominantly cosmic-ray nucleonic mechanism at higher energies to a cosmic-ray electron mechanism at the lower energies. This provides a most important and direct means of probing the cosmic-ray electrons as a function of galactic position...

188. Nuclear Science Symposium, 23rd, Scintillation and Semiconductor Counter Symposium, 15th, and Nuclear Power Systems Symposium, 8th, New Orleans, La., October 20-22, 1976, Proceedings - Wagner, L. J.
The volume includes papers on semiconductor radiation detectors of various types, components of radiation detection and dosimetric systems, digital and microprocessor equipment in nuclear industry and science, and a wide variety of applications of nuclear radiation detectors. Semiconductor detectors of X-rays, gamma radiation, heavy ions, neutrons, and other nuclear particles, plastic scintillator arrays, drift chambers, spark wire chambers, and radiation dosimeter systems are reported on. Digital and analog conversion systems, digital data and control systems, microprocessors, and their uses in scientific research and nuclear power plants are discussed. Large-area imaging and biomedical nucleonic instrumentation, nuclear power plant safeguards, reactor instrumentation,...

189. NASA thermionic-conversion program - Morris, J. F.; Lundholm, J. G.
The NASA applied research and technology (ART) program for thermionic energy conversion (TEC) is progressing effectively. Current out-of-core emphases allow converter material and design freedoms previously prohibited by in-core nucleonic and geometric restrictions. As a result, potential improvements indicate possibilities for severalfold increases in efficiencies. The new TEC-ART program concentrated initially on low-work-function collectors and interelectrode-loss reduction and revealed much in a short time. For example, arc-drop studies verified the necessity of stable emitters that operate well with little or no adsorbed cesium. This new emission capability coupled with improved collectors that maintain performance with emitter-vapor deposit accumulations are requisites...

190. Transient cosmic ray increase associated with a geomagnetic storm - Kudo, S.; Wada, M.; Tanskanen, P.; Kodama, M.
On the basis of worldwide network data of cosmic ray nucleonic components, the transient cosmic ray increase due to the depression of cosmic ray cutoff rigidity during a severe geomagnetic storm was investigated in terms of the longitudinal dependence. Multiple correlation analysis among isotropic and diurnal terms of cosmic ray intensity variations and Dst term of the geomagnetic field is applied to each of various station's data. It is shown that the amplitude of the transient cosmic ray increase associated with Dst depends on the local time of the station, and that its maximum phase is found in the evening...

191. The longitudinal galactic cosmic ray intensity modulation in a diffusive and a scatter-free model of the inner heliosphere - Morfill, G.; Scholer, M.; Van Hollebeke, M. A. I.
Measurements of energetic solar flare electrons, Jovian electrons, and low-energy solar protons have led to the suggestion that the inner heliosphere is essentially scatter free. Consideration is given to a model in which scattering is only important within the corotating interaction regions (CIR's), while the cavity formed by the CIR's in the inner heliosphere is scatter free, as compared to an interplanetary diffusion model wherein scattering is determined by the solar wind and magnetic field microstructure everywhere in the heliosphere. The two models are compared in terms of the solar wind stream associated Forbush decreases at 1 AU and the...

192. Significance of medium energy gamma ray astronomy in the study of cosmic rays - Fichtel, C. E.; Kniffen, D. A.; Thompson, D. J.; Bignami, G. F.; Cheung, C. Y.
Medium energy (about 10 to 30 MeV) gamma ray astronomy provides information on the product of the galactic electron cosmic ray intensity and the galactic matter to which the electrons are dynamically coupled by the magnetic field. Because high energy (greater than 100 MeV) gamma ray astronomy provides analogous information for the nucleonic cosmic rays and the relevant matter, a comparison between high energy and medium energy gamma ray intensities provides a direct ratio of the cosmic ray electrons and nucleons throughout the galaxy. A calculation of gamma ray production by electron bremsstrahlung shows that: bremsstrahlung energy loss is probably...

193. Observations of the supernova remnants Cas-A and Tycho with the HEGRA stereoscopic IACT system - Uhlhofer Wiedner For; G. Pühlhofer; H. Völk; C. A. Wiedner; For The Hegra Collaboration; D- Heidelberg
Recently, young supernova remnants (SNR) from type Ia Supernovae (SNe) have become targets of interest for TeV gamma-ray astronomy. This prompted the HEGRA collaboration to extensively observe Tycho's SNR in 1997 and 1998 with its stereoscopic IACT system. The HEGRA IACT system was also used to observe the young SNR Cas-A. Although considered to be the result of a SN type Ib, the detected strong nonthermal X-ray emission makes this SNR a promising candidate for TeV gamma-ray emission. Given the spatial resolution of the system, both sources are still nearly pointlike. Therefore, the data samples yield an emission sensitivity close...

194. Multifragmentation in Relativistic Heavy Ion Reactions - Trautmann Gesellschaft Fur; W. Trautmann
Multifragmentation is the dominant decay mode of heavy nuclear systems with excitation energies in the vicinity of their binding energies. It explores the partition space associated with the number of nucleonic constituents and it is characterized by a multiple production of nuclear fragments with intermediate mass. Reactions at relativistic bombarding energies, exceeding several hundreds of MeV per nucleon, have been found very efficient in creating such highly excited systems. Peripheral collisions of heavy symmetric systems or more central collisions of mass asymmetric systems produce spectator nuclei with properties indicating a high degree of equilibration. The observed decay patterns are well...

195. Threshold Behaviour of Meson-Nucleon-S - Vertexfunctions And Determination; F. Kleefeld
A new method for the determination of the spin-1/2-3/2-mixing angle and the range parameter of the quarkmodel wavefunction of the resonance S \Gamma 11 (1535) is presented. The method ist based on a quantitative calculation of the total cross section of pp ! ppj at threshold. The quantitative on-shell treatment of ISI and FSI is discussed. INTRODUCTION Nearly all calculations for the determination of mixing angles between different spincomponents of baryon wavefunctions are based on spectroscopic models. Beside their advantages these models also contain some problems which are not dissolved yet. The goal of the presented work is an independent...

196. Propagation of Ultra High Energy Protons and Gamma Rays over Cosmological Distances and Implications for Topological Defect Models - Protheroe And; R. J. Protheroe; P. A. Johnson
We describe the results of a hybrid matrix--Monte Carlo calculation of cascading of UHE cosmic rays and fl-rays through the cosmic background radiation fields over cosmological distances. We calculate the fl-ray and neutrino emission that results from the cascade, as well as the effect of cascading on the primary spectrum. We discuss the results for various cosmic ray injection spectra and primary species. Certain models for the production of the highest energy cosmic rays are ruled out. 1 Introduction It was first noted by Greisen [1], and Zatsepin and Kuz'min [2] (GZK) that the nucleonic component of UHE cosmic rays...

197. Propagation of UHE Protons over Cosmological Distances - Protheroe And; R. J. Protheroe; P. A. Johnson
We describe the results of a hybrid matrix--Monte Carlo calculation of cascading of UHE cosmic rays through the cosmic background radiation fields over cosmological distances. We calculate the fl-ray and neutrino emission that results from the cascade, as well as the effect of cascading on the primary spectrum. We discuss the results for various cosmic ray injection spectra. 1 Introduction It was first noted by Greisen [1], and Zatsepin and Kuz'min [2] that the nucleonic component of UHE cosmic-rays above 10 20 eV will be severely attenuated in the cosmic microwave background due primarily to photopion production interactions with the...

198. Nonthermal X-ray emission from young supernova remnants - E. Van Der Swaluw; Bram Achterberg
Abstract. The Galactic (nucleonic) cosmic-ray spectrum up to the knee (E ∼ 10 15 eV) is believed to originate from acceleration processes occurring at supernova remnant shocks. This idea is confirmed by theoretical predictions, which give a similar estimate for the maximum particle energy, which can be reached at these shocks. Electrons with energies E ∼ 10 14 eV radiate X-ray photons in the ∼ 10 − 100 µG magnetic fields present in many young supernova remnants. These electrons (near the knee), give rise to a nonthermal X-ray component in the spectrum of young supernova remnants. Recent observations of SN1006...

199. CHANDRA/VLA Follow-up of TeV J2032+4131, the Only Unidentified TeV Gamma-ray Source - Butt, Yousaf; Benaglia, Paula; Combi, Jorge; Corcoran, Michael; Dame, Thomas; Drake, Jeremy; Bernado, Marina Kaufman; Milne, Peter; Miniati, Francesco; Pohl, Martin; Reimer, Olaf; Romero, Gustavo; Rupen, Michael
The HEGRA Cherenkov telescope array group recently reported a steady and extended unidentified TeV gamma-ray source lying at the outskirts of Cygnus OB2. This is the most massive stellar association known in the Galaxy, estimated to contain ~2600 OB type members alone. It has been previously argued that the large scale shocks and turbulence induced by the multiple interacting supersonic winds from the many young stars in such associations may play a role in accelerating Galactic cosmic rays. Indeed, Cyg OB2 also coincides with the non-variable MeV-GeV range unidentified EGRET source, 3EG 2033+4118. We report on the near-simultaneous follow-up observations of the extended TeV source region with the CHANDRA...

200. Study of Photon Dissociation in Diffractive Photoproduction at HERA - Collaboration, ZEUS; al, M. Derrick et
Diffractive dissociation of quasi-real photons at a photon-proton centre of mass energy of W ~ 200 GeV is studied with the ZEUS detector at HERA. The process under consideration is gamma p -> X N, where X is the diffractively dissociated photon system of mass M_X and N is either a proton or a nucleonic system with mass M_N < 2GeV. The cross section for this process in the interval 3 < M_X < 24 GeV relative to the total photoproduction cross section was measured to be sigma^partial_D / sigma_tot = 6.2 +- 0.2(stat) +- 1.4(syst)%. After extrapolating this result to the mass interval of m_phi^2 <...

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