A tunable, high-intensity picosecond dye laser system has been employed with electron energy analysis to investigate the dynamics of (3+1) resonance-enhanced multiphoton ionization of H{sub 2} via different vibrational levels of its B{sub 1}{Sigma}{sub u}{sup +} and C{sup 1}{Pi}{sub u} electronic states. We observe production of molecular ions in various vibrational levels, with a shift to increased population of lower vibrational states of H{sub 2}{sup +} consistent with the a.c. Stark shift of the correspondingly lower vibrational levels of the C state into resonance with the three- photon energy of the laser. Clear evidence of direct dissociation of H{sub 2} followed by single-photon ionization of the excited H atom is observed as well. Above threshold ionization of these two processes occurs readily. We also find that dissociative ionization is an increasingly important ionization pathway as the wavelength is increased. Finally, we see evidence of a new ionization pathway, which we assign to photoionization into a transient bound state created by the avoided crossing of the first repulsive electronic state of H{sub 2}{sup +}, {vert bar}2p{sigma}{sub u}, n{r angle}, with the single-photon-dressed ground state of H{sub 2}{sup +}, {vert bar}1s{sigma}{sub g},n + 1{r angle}. 6 refs., 2 figs.

A Monte Carlo code has been developed to simulate individual electron interactions. The code has been instrumental in determining the range of validity for the widely used condensed history method. This task was accomplished by isolating and testing the condensed history assumptions. The results show that the condensed history method fails for low energy electron transport due to inaccuracies in energy loss and spatial positioning. 19 refs., 21 figs., 1 tab.

Upon leaving the damping ring, the SLC beam passes through the Ring-to-Linac transfer line (RTL), the linac, and the arcs on its way to the collision point. In an earlier paper calculations of the longitudinal distributions of the lengthened damping ring beam were presented, calculations that agreed remarkably well with measurements. In this paper we propagate the damping ring distributions through the rest of the machine. Among the effects that are included in the calculations are the curvature of the compressor rf and the limited energy aperture in the RTL, the wakefields in the linac, and the momentum compaction in the arcs. 12 refs., 7 figs., 1 tab.

The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. We present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9 GeV electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high proton flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in <500 hr of operation. 5 refs., 3 figs., 2 tabs.

The CEBAF accelerator contains approximately 2500 power supplies, 340 klystrons, and 800 beam monitors. The operation of such a complex machine requires a control system which can provide a high degree of automation with strong support by simulation and modeling programs.\nWe present the architecture and first results of a control system which allows one the use of identical operation procedures and interfaces for operation of the real accelerator and high-level accelerator simulation programs. The interfaces were developed using TACL (Thaumaturgic Automated Control Logic) control software, developed at CEBAF for accelerator control. This setup provides the capability to: (1) test and debug the various operation procedures before the completion of the accelerator, (2) execute machine simulations under realistic environmental conditions, and (3) preview and evaluate the effectiveness of operational procedures during run time. The optimized simulation program adds only two seconds to

Actinide-doped SRL 165 type glass was reacted in J-13 groundwater at 90{degrees}C for times up to 278 days. The reaction was characterized by both solution and solid analyses. The glass was seen to react nonstoichiometrically with preferred leaching of alkali metals and boron. High resolution electron microscopy revealed the formation of a complex layer structure which became separated from the underlying glass as the reaction progressed. The formation of the layer and its effect on continued glass reaction are discussed with respect to the current model for glass reaction used in the EQ3/6 computer simulation. It is concluded that the layer formed after 278 days is not protective and may eventually become fractured and generate particulates that may be transported by liquid water. 5 refs., 6 figs., 3 tabs.

Actinide-doped SRL 165 type glass was reacted in J-13 groundwater at 90{degree}C for times up to 278 days. The reaction was characterized by both solution and solid analyses. The glass was seen to react nonstoichiometrically with preferred leaching of alkali metals and boron. High resolution electron microscopy revealed the formation of a complex layer structure which became separated from the underlying glass as the reaction progressed. The formation of the layer and its effect on continued glass reaction are discussed with respect to the current model for glass reaction used in the EQ3/6 computer simulation. It is concluded that the layer formed after 278 days is not protective and may eventually become fractured and generate particulates that may be transported by liquid water. 5 refs., 5 figs. , 3 tabs.

A critical review and a reassessment of data reviewed in NCRP Report 106 on effects of hot particles'' on the skin of pigs, monkeys, and humans were made. Our analysis of the data of Forbes and Mikhail on effects from activated UC{sub 2} particles, ranging in diameter from 144 {mu}m to 328 {mu}m, led to the formulation of a new model for prediction of both the threshold for acute ulceration and for ulcer diameter. A dose of 27 Gy at a depth of 1.33 mm in tissue in this model will result in an acute ulcer with a diameter determined by the radius over which this dose (at 1.33-mm depth) extends. Application of the model to the Forbes-Mikhail data yielded a threshold'' (5% probability) of 6 {times} 10{sup 9} beta particles from a point source on skin of mixed fission product beta particles, or about 10{sup 10} beta particles from Sr--Y-90, since few of the Sr-90 beta particles reach this depth. The data of Hopewell et al. for their 1 mm Sr-Y-90 exposures were also analyzed with the above model and yielded a predicted threshold of 2 {times} 10{sup 10} Sr-Y-90 beta particles for a point source on skin. Dosimetry …

A software system for control of accelerator physics parameters of the Advanced Light Source (ALS) is being designed and implemented at LBL. Some of the parameters we wish to control are tunes, chromaticities, and closed orbit distortions as well as linear lattice distortions and, possibly, amplitude- and momentum-dependent tune shifts. In all our applications, the goal is to allow the user to adjust physics parameters of the machine, instead of turning knobs that control magnets directly. This control will take place via a highly graphical user interface, with both a model appropriate to the application and any correction algorithm running alongside as separate processes. Many of these applications will run on a Unix workstation, separate from the controls system, but communicating with the hardware database via Remote Procedure Calls (RPCs).

We have developed a method that uses an arbitrary symplectic tracking code to generate an exactly symplectic full-turn or multi-turn map. The map is obtained from a generating function, which is a finite Fourier series in the final angle coordinates, the Fourier coefficients being represented as a B-spline series in the initial action coordinates. We achieve fast iteration of this implicitly defined map, and good accuracy. As a first application, we treat a simplified model of arcs of the SSC. 5 refs., 1 fig.

The ability of existing analytical and numerical tools to predict beam performance at the short bunch lengths and high peak currents characteristic of contemporary accelerator designs is discussed. Recent advances in calculating the high frequency behavior of impedance and in describing bunched-beam collective dynamics are highlighted. A critical review is presented of outstanding problems that must be addressed before a thorough description of short, intense bunches is obtained.

The proposed asymmetric energy B Factory to be built in the PEP tunnel at SLAC will require a highly effective and profuse source of low emittance electron and positron bunches. The B factory will consist of two rings of equal size, a 9 GeV electron ring and a 3.1 GeV positron ring, each with 1658 bunches with total circulating currents of 1.5 and 2.1 amperes respectively. As the luminosity lifetime of the collider is expected to be about two hours, the injector should be capable of filling the rings in a small fraction of an hour. It turns out that with some simple modifications, the SLC linac with its damping rings and positron source is ideally suited to fulfill this function effectively. The overall injection system is described in this paper. 4 figs., 2 tabs.

Tracking studies of transition crossing in the Main Injector have shown that the Johnsen effect is the dominant cause of beam loss and emittance blow up. To suppress this effect one has to have control over {alpha}{sub 1} (dispersion of the momentum compaction factor {alpha}). Various {gamma}{sub t} jump configurations are examined and the resulting changes in {alpha}{sub 1} are assessed. These results are further validated by comparison between the simulation and simple analytic {alpha}{sub 1}--formulas derived for a model FODO lattice with full chromaticity compensation in the presence of an eddy current sextupole component. A scheme involving the introduction of a dispersion wave in the arcs of the Main Injector, around transition time, seems to be promising if one regards the strength of the eddy current sextupole family as an external knob'' to control values of {alpha}{sub 1}.

A pulsed, split-parallel plate chopper has been designed built, and installed as part of the preinjector of the SSRL Injector. Its function is to allow the linear accelerator three consecutive S-band bunches from the long bunch train provided by a RF gun. A permanent magnet deflector (PMD) at the chopper entrance deflects the beam into an absorber when the chopper pulse is off. The beam is swept across a pair of slits at the beam output end when a 7 kV, 10-ns rise-time pulse passes in the opposite direction through the 75 {Omega} stripline formed by the deflecting plates. Bunches exiting the slits have their trajectories corrected by another PMD, and enter the linac. Beam tests demonstrate that the chopper functions as expected. 9 refs., 5 figs.

An electronic system is presented which detects synchrotron oscillations of individual bunches with 4 ns separation. The system design and performance are motivated by the requirements of the proposed B factory facility at SLAC. Laboratory results are presented which show that the prototype is capable of measuring individual bunch phases with better than 0.5 degree resolution at the 476 MHz RF frequency. 13 refs., 6 figs., 1 tab.

An electronic system is presented which detects synchrotron oscillations of individual bunches with 4 ns separation. The system design and performance are motivated by the requirements of the proposed B Factory facility at SLAC. Laboratory results are presented which show that the prototype is capable of measuring individual bunch phases with better than 0.5 degree resolution at the 476 MHz RF frequency.

The SLAC B-factory design, with over 1600 high current bunches circulating in each ring, will require a feedback system to avoid coupled-bunch instabilities. A computer model of the storage ring, including the RF system, wave fields, synchrotron radiation loss, and the bunch-by-bunch feedback system is presented. The feedback system model represents the performance of a fast phase detector front end (including system noise and imperfections), a digital filter used to generate a correction voltage, and a power amplifier and beam kicker system. The combined ring-feedback system model is used to study the feedback system performance required to suppress instabilities and to quantify the dynamics of the system. Results are presented which show the time development of coupled bunch instabilities and the damping action of the feedback system. 3 refs., 5 figs., 2 tabs.

Measurements of more than 1000 new magnets are needed for the Main Injector Project at Fermilab. In order to achieve efficiency and accuracy in measurements, we chose a database driven design for control of the measurement system. We will use a relational database to describe the measurement subjects and equipment. A logbook system defined in the database will provide for prescription of measurements to be carried out, description of measurements as they are carried out, and a comment database for less structured information. The operator interface will be built on X-windows. This paper will describe our system design. 2 refs.

The Main Ring Quadrupoles have been used in the Fermilab Main Ring and will be utilized in the proposed Fermilab Main Injector. Utilizing a rotating coil harmonic measurement system, a sample of more than 35 Fermilab Main Ring Quadrupoles have been measured. The asymmetric design of these magnets provides many easily measured harmonic coefficients. Results for harmonic coefficients at various excitation levels are presented. 5 refs., 3 figs., 1 tab.

The Mevva (metal vapor vacuum arc) ion source provides high current beams of multiply-charged metal ions suitable for use in heavy ion synchrotrons as well as for metallurgical ion implantation. Pulsed beam currents of up to several amperes can be produced at ion energies of up to several hundred keV. Operation has been demonstrate for 48 metallic ion species: Li, C, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Ba, La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er, Yb, Hf, Ta, W, Ir, Pt, Au, Pb, Bi, Th and U. When the source is operated optimally the rms fractional beam noise can be as low as 7% of the mean beam current; and when properly triggered the source operates reliably and reproducibly for many tens of thousands of pulses without failure. In this paper we review the source performance referred specifically to its use for synchrotron injection. 15 refs., 3 figs.

For future linear colliders, with very small emittances and beam sizes and demanding tolerances on final focus system alignment and magnet errors, it becomes increasingly important to use the beam as a diagnostic tool. We report here procedures we have identified and will be implemented in the Final Focus Test Beam at SLAC incorporating (1) quadrupole strength changes, (2) central orbit modifications, (3) spot size measurements, and (4) beam stability monitoring. 3 refs., 4 figs., 3 tabs.

We review the tolerances associated with the Final Focus Test Beam (FFTB). We have computed the acceptability window of the input beam for orbit jitter, emittance beta functions mismatch, incoming dispersion and coupling; tolerances on magnet alignment, strength and multipole content; and the initial tuneability capture of the line. 2 refs., 1 fig.

Based on a simple K-cloud model, as well as the Gross-Neveu and the Nambu-Jona-Lasinio model, it is predicted that the s{bar s} sea in a proton is not charge symmetric at large Bjorken-x. The s quarks are shifted to larger values of x{sub bj} than the {bar s} quarks. Furthermore these large x{sub bj} s quarks carry a negative polarization. 9 refs., 2 figs.

An overview is given of the Final Focus Test Beam (FFTB) that is being constructed as a prototype final focus system for a future electron-positron linear collider. This beam line will use as input the 50 GeV electron beam from the SLC linac, and is designed to reduce the transverse dimensions of the beam spot at the focal point to 1 {mu}m. 5 refs., 2 figs., 1 tab.