Search

The e + e − -storage ring DORIS II provides polarized beams with polarizations up to 80% in the energy range of the ϒ ′ meson. The method of resonance depolarization allows the average beam energy to be determined to a precision of ±0.1 MeV. An energy scan of the hadronic cross section over the resonance range with the detectors ARGUS and Crystal Ball determines the ϒ ′ mass to be (10023.1 ± 0.4) MeV.

Gamma-ray astronomy which includes the spectral region from above approximately 100 keV to greater than or equal to 1000 GeV permits investigation of the most energetic photons originating in our galaxy and beyond and provides the most direct means of studying the largest transfers of energy occurring in astrophysical processes. Of all the electromagnetic spectrum, high-energy gamma-ray astronomy measures most directly the presence and dynamic effects of the energetic charged cosmic ray particles, element synthesis, and particle acceleration. Further, gamma rays suffer negligible absorption or scatterings as they travel in straight paths; hence, they may survive billions of years and still reveal their source. The high energy processes in stellar objects (including our Sun), the dynamics of the cosmic-ray gas, the formation of clouds and nebulae, galactic evolution and even certain aspects of cosmology and the origin of the universe may be explored by gamma-ray observations.

The risks and costs of the present method of visualizing the coronary arteries have limited the use of coronary angiography in long-term serial studies needed to establish the natural history of coronary atherosclerosis and its response to interventions. A less invasive method, in which the contrast agent is administered intravenously, has been developed using synchrotron radiation as the illuminating source. The present report describes the initial results in human subjects. The findings indicate that transvenous coronary angiograms can be acquired in this manner. Further refinements in the x-ray imaging system are expected to result in increased x-ray fluence and improved image quality.

Using the Crystal Ball detector at thee +e− storage ring DORIS-II, we have searched for the hadronic transitions Υ(2S)→ηΥ(1S) and Υ(2S)→π0Υ(1S) in exclusive decays where the Υ(1S) decays into ane +e− or aµ + µ - pair and the η and π0 are detected by their decay modes η→γγ, η→γγ and π0→γγ. From the number of observed events we derive, after consideration of possible background sources, upper limits on the branching ratiosB(Υ(2S)→ηΥ(1S))

The data acquisition system for the Crystal Ball project at SLAC is described. A PDP-11/t55 using RSX-11M connected to the SLAC Triplex is the basis of the system. A "physics pipeline" allows physicists to write their own equipment-monitoring or physics tasks which require event sampling. As well, an interactive analysis package (MULTI) is in the pipeline. Histogram collection and display on the PDP are implemented using the Triplex histogramming package. Various interactive event displays are also implemented.

Using the Crystal Ball detector operating at the DORIS II storage ring we have measured the leptonic partial widthsГ ee of the Υ(1S) and Υ(2S) resonances. We find $$\Gamma _{ee} (\Upsilon (1S)) = 1.34 \pm 0.03 \pm 0.06keV$$ and $$\Gamma _{ee} (\Upsilon (2S)) = 0.56 \pm 0.04 \pm 0.02keV.$$ The effect onГ ee of applying different prescriptions for radiative corrections is discussed. We also measureR, the ratio of non-resonant hadronic cross section to the Born cross section of μ pair production, at c.m. energyW=9.39 GeV to beR=3.48±0.04±0.16.

The Crystal Ball detector at the Doris II storage ring at DESY was used to search for the exotic decay processes τ →e γ , τ →e π 0 , and τ →e η . No signal was observed. We obtained the following 90% CL upper limits on the branching fractions: B ( τ →e γ ) −4 , B ( τ →e π 0 ) −4 , B ( τ →e η ) −4 .

The mirror nuclei of tritium and helium-3 have been studied by the method of elastic electron scattering. Absolute cross sections have been measured for incident electron energies in the range 110-680 MeV at scattering angles lying between 40 and 135\ifmmode^\circ\else\textdegree\fi{} in this energy range. The data have been interpreted in a straightforward manner and form factors are given for the distributions of charge and magnetic moment in the two nuclei over a range of four-momentum transfer squared 1.0-8.0 ${\mathrm{F}}^{\ensuremath{-}2}$. Model-independent radii of the charge and magnetic-moment distributions are given and an attempt is made to deduce form factors describing the spatial distribution of the protons in tritium and helium-3.

A total absorption Nal(TI) detector can be used to define the energy of an incident electron, or γ-ray, to a precision of I to 2 per cent in the range of 4 to 14 GeV.

We have searched for radiative decays of the ϒ(1S) resonance, ϒ(1S)→γX, whereX is one of the mesons η, η′f2 (1270),f2 (1720), or a narrow resonance with mass less than 3 GeV/c2 which decays into either π0π0 or ηη. The mesons are identified in their all-neutral decay modes. Since we do not find any such decays, we calculate upper limits on the corresponding branching ratios. These limits are compared to theoretical predictions and to the corresponding branching ratios measured in radiativeJ/Ψ decays.

The aim was the development of an angiographic method and appropriate equipment for imaging with x-rays the coronary arteries in a non-invasive manner. Successive steps involved studies with phantoms, live animals and finally with human subjects. Clinical evaluation of human coronary arteries remains a goal of this and a continuing project, and steps along the way to such an achievement are in process. Transvenous injection of a dye using the method of iodine dichromography near 33.2 keV, the K-edge of iodine, forms the basis of the method. 11 refs.

In concluding this discussion it may be appropriate to return to the theme introduced earlier and raise the question once again of the deeper, and possibly philosophical, meaning of the term "elementary" particle. As we have seen, the proton and neutron, which were once thought to be elementary particles, are now seen to be highly complex bodies. It is almost certain that physicists will subsequently investigate the constituent parts of the proton and neutron—the mesons of one sort or another. What will happen from that point on? One can only guess at future problems and future progress, but my personal conviction is that the search for ever-smaller and ever-more-fundamental particles will go on as long as man retains the curiosity he has always demonstrated ( 29 ).

The electron-and bremsstrahlung-induced fission cross sections of the isotopes $_{92}^{238}\mathrm{U}$, $_{83}^{209}\mathrm{Bi}$, $_{82}^{208}\mathrm{Pb}$, $_{70}^{174}\mathrm{Yb}$, and $_{62}^{154}\mathrm{Sm}$ have been measured over the energy range 60-1000 MeV. The consistency of the theoretical expressions for the bremsstrahlung spectrum and the virtual-photon spectrum associated with the electron has been tested using the experimental data. Good agreement was obtained on the assumption of $E1$ or $M1$ transitions. The photofission cross sections obtained on the basis of this procedure were analyzed in terms of the photon-interaction cross section and the fission probability. It was found that the rapid increase in the photofission cross section with increasing energy for $^{209}\mathrm{Bi}$ and the lighter isotopes is due to the normal increase in fission probability with energy, and not to the onset of $\ensuremath{\pi}$-meson photoproduction as was previously suggested. The photon-interaction cross section predicted by the quasideuteron model seems to account for all of the interaction leading to fission in these elements, even at energies above the threshold for $\ensuremath{\pi}$-meson production. In the case of $^{238}\mathrm{U}$, however, since the fission probability is approximately constant as a function of energy, the fission cross-section behavior reflects the characteristics of the total photon-interaction cross section. In the latter case it was found that the $\ensuremath{\pi}$-meson photoproduction and the quasideuteron interaction are both involved in producing excitation leading to fission. The difference between the behavior of $^{238}\mathrm{U}$ and the lighter isotopes is understood in terms of differences in fission barriers and differences in energy deposition associated with the two interaction mechanisms. The asymmetric fission of $^{238}\mathrm{U}$ at high electron or bremsstrahlung energies is also explained on this basis.

The Crystal Ball detector at thee+e− storage ring DORIS-II has been used to search for radiativeB meson decays, especially of the typeb→sγ. No monoenergetic γ-lines have been found in the inclusive photon spectrum from У(4S) decays, and upper limits are obtained for radiative decays ofB mesons to various strange mesons and to theD*. Integrating the photon spectrum over the corresponding energy range, we find $$BR(B \to \gamma X)< 2.8 \times 10^{ - 3} ,$$ at 90% confidence level for the mass range 892 MeV ≦MX≦2045 MeV.

The Crystal Ball Collaboration has measured the energy spectrum of electrons from semileptonicB meson decays at thee + e − storage ring DORIS II. Branching ratios and weak mixing angles of the Kobayashi-Maskawa matrix are determined using several models for the hadronic matrix elements. We obtain the branching ratio for semileptonic.B decays to charmed states BR(B→evX c )=(11.7±0.4±1.0)%. Our result for the corresponding Kobayashi-Maskawa matrix element is |V cb |=0.052±0.006. The model dependence of both results is included in the error. We have not observed semileptonicB decays to non-charmed mesons. Analyzing the measured electron spectrum above 2.4 GeV, where nob→c decays contribute, we find BR(B→evX u )/BR(B→evX c )

A method using an accelerator and thin targets is suggested for investigating very small energy losses in highenergy electron or proton scattering events. (C.E.S.)