This article is devoted to electron beam distortions in the “electron compressor” setup for beam-beam compensation in the Tevatron collider. The effects of electron space charge force and the interaction of the electron beam with the impacting elliptical antiproton beam are studied. We make an estimate of the longitudinal magnetic field necessary to keep the electron beam distortions low.

We study the dynamics of transverse oscillations near the linear coupling resonance excited by a pair of skew quadrupoles at the Laboratório Nacional de Luz Síncrotron UVX electron storage ring through the analysis of the beam profile. Transverse coherent oscillations were excited with a fast kicker and the profile of the oscillating beam was observed by focusing visible synchrotron radiation from a bending magnet onto a fast charge-coupled device camera. Using a single resonance approximation, we calculated the border of the time-averaged transverse beam profile as a function of the complex coupling coefficient $\kappa$, which characterizes the distribution of coupling fields along the storage ring. A least-squares fit of the calculated beam profile border to the experimentally obtained isointensity contours provided a new method to determine both the modulus and the phase of $\kappa$. The values obtained for the modulus are in good agreement with those from the conventional normal mode tune separation technique, and the values obtained for the phase of $\kappa$ agree with calculations based on the model lattice and the known skew quadrupole distribution.

A new scheme of ${\mathrm{H}}^{-}$ charge-exchange injection without stripping foils is proposed. It is composed of a neutralizer of the ${\mathrm{H}}^{-}$ beam using Lorentz stripping, the colliding system of a high power laser and the ${\mathrm{H}}^0$ beam to excite ${\mathrm{H}}^0$ atoms to the $3P$ state using the Rabi oscillation, and a magnet to strip the ${\mathrm{H}}^0\left(3P\right)$ to a proton beam by Lorentz stripping. The necessary laser wavelength, laser power, magnetic-field gradient, and maximum magnetic field are estimated for a beam energy from 1.0 to 3.0 GeV. The result shows that such a scheme is sufficiently feasible for ${\mathrm{H}}^{-}$ beams with an energy discussed here.

We have studied the autophasing conditions in long linear accelerators for a phase advance scaling along the machine instead of the usual beta scaling. A new lattice scaling provides the damping of the resonant enlargement of bunches in transverse wakefields with small required correlated energy spread in the bunch. In addition, such an approach allows one to keep the amplitude of coherent betatron oscillations small by a proper choice of the phase advance at the first cell. It is shown that the scaling of the phase advance per cell gives significant advantages with respect to singlebunch and multibunch instabilities.

Results are presented for electron beam transport experiments in a 1-m-long straight section consisting of a solenoid and five short printed-circuit quadrupoles. A linear computer code for rms envelope matching, SPOT, is used for channel design, while final simulations with more realistic elements are obtained with a $2\frac{1}{2}\mathrm{D}$ version of WARP, a particle-in-cell code. Reasonable agreement is found between calculations and the effective beam envelope obtained from pictures of the beam on a movable phosphor screen. The results validate, within experimental errors, the use of short magnetic quadrupoles for the transport of space-charge dominated beams. The straight section constitutes the prototype matching section for an electron recirculator to be built at the University of Maryland.

We report experimental results on the high peak current electron beam generated at the Argonne Wakefield Accelerator facility for wakefield applications. The facility produces bunch charges in the range 15–100 nC by using a photocathode based RF electron gun. The energy of the beam is 14 MeV. Our measurements show that for bunches of 100 nC, the pulse length can be as short as 30 ps. A detailed systematic study of pulse length versus charge is reported, as well as comparisons with numerical simulations. Dark current beam loading in the high field RF gun is also discussed.

Transverse mode coupling instability is one of the major limitations of a single bunch current in storage rings. Until now it has appeared in large electron-positron machines, while its presence in proton colliders has not been observed. This paper describes a theoretical analysis of the effect of longitudinal variation of the betatron tune on the transverse mode coupling instability. This variation can be introduced by an RF quadrupole. In the result, the instability threshold could be significantly increased when a modulation of the betatron frequency is comparable with the synchrotron tune.

The fast head-tail instability with space charge is studied using series expansion techniques, numerical simulations, and a new formulation which allows for precise estimates of growth rates and thresholds. In regimes where they are reliable, all three techniques predict that space charge suppresses the fast head-tail instability. It is found that the series expansion techniques are unreliable for parameter regimes commonly employed in hadron accelerators. The numerical techniques are less prone to error, but the computational requirements become severe as space charge tune shifts increase. The new model has neither of these problems, but it underestimates the benefits of chromaticity, at least in its simplest form.

The exact solution of the classical nonlinear equation of motion for a relativistic electron in the field of two electromagnetic (EM) waves is obtained. For the particular case of the linearly polarized standing EM wave in the planar optical cavity, intensity of the nonlinear Compton scattering, the time of flight, and the momentum variation after the relativistic electron passes along the cavity axis are calculated in weak and strong field limits. These effects depend on the initial phase of the EM wave at the electron entrance into the cavity and can be used for producing, diagnostics, and acceleration of relativistic electron (positron) microbunches.

The proton driver for the muon collider must produce short pulses of protons in order to facilitate muon cooling and operation with polarized beams. In order to test methods of producing these bunches, we have operated the alternating-gradient synchrotron near transition and studied procedures which involved moving the transition energy ${\gamma }_t$ to the beam energy. We were able to produce stable bunches of $3–5\times {10}^{12}$ protons with rms widths of $\sigma =2.0\mathrm{}–2.7\mathrm{ns}$ for longitudinal bunch areas of $1.5\mathrm{eV}\mathrm{s}$, in addition to making measurements of the lowest two orders of the momentum compaction factor.

This article presents results of wideband seismic measurements at the Fermilab site, namely, in the tunnel of the Tevatron and on the surface nearby, as well as in two deep tunnels in the Illinois dolomite, thought to be a possible geological environment of the Fermilab future accelerators.

A detailed comparison between photon acceleration and frequency-domain interferometry, for laser wakefield diagnostics, is presented here. The dispersion effects on the probe beam and the implications of an arbitrary phase velocity of the plasma wave are discussed for both diagnostic techniques. In the presence of a large amplitude plasma wave and for long interaction distances, significant frequency up-shifts are observed. The importance of this effect on the determination of the phase and frequency shift measurements given by the two techniques is also analyzed. The accuracy of both diagnostics is discussed and some of their technical problems are reviewed.

The Cornell electron storage ring (CESR) phase-III upgrade plan includes very strong permanent magnet quadrupoles in front of the cryostat for the superconducting quadrupoles and physically as close as possible to the interaction point. Together with the superconducting quadrupoles, they provide tighter vertical focusing at the interaction point. The quadrupoles are built with neodymium iron boron (NdFeB) material and operate inside the 15 kG solenoid field. Requirements on the field quality and stability of these quadrupoles are discussed and test results are presented.

Luminosity-driven channeling extraction has been observed for the first time using a 900 GeV circulating proton beam at the superconducting Fermilab Tevatron. The extraction efficiency was found to be about 30%. A 150 kHz beam was obtained during luminosity-driven extraction with a tolerable background rate at the collider experiments. A 900 kHz beam was obtained when the background limits were doubled. This is the highest energy at which channeling has been observed.

We recently developed a general analysis for an azimuthally asymmetric rectangular slot in the inner conductor of a coaxial liner, which allowed us to investigate the coupling impedance numerically. In the present paper we obtain analytic expressions for a small hole of arbitrary shape. Specifically, we go beyond the quasistatic (Bethe) approximation to explore and understand the structure of the impedance in the frequency region near the cutoffs of the inner beam pipe and outer coaxial structure. Finally, we extend our analytic analysis to a hole in a wall of finite thickness.

We present an empirical investigation of the correcting coils behavior used to homogenize the field distribution of the race-track microtron accelerator end magnets. These end magnets belong to the second stage of the 30.0 MeV cw electron accelerator under construction at IFUSP, the race-track microtron booster, in which the beam energy is raised from 1.97 to 5.1 MeV. The correcting coils are attached to the pole faces and are based on the inhomogeneities of the magnetic field measured. The performance of these coils, when operating the end magnets with currents that differ by $\pm 10\%$ from the one used in the mappings that originated the coils copper leads, is presented. For one of the magnets, adjusting conveniently the current of the correcting coils makes it possible to homogenize field distributions of different intensities, once their shapes are practically identical to those that originated the coils. For the other one, the shapes are changed and the coils are less efficient. This is related to intrinsic factors that determine the inhomogeneities. However, we obtained uniformity of 0.001% in both cases.

First results from the research and development program PARRNE (Production d'Atomes Radioactifs Riches en NEutrons) are presented. Its aim is the investigation of the optimum conditions for the production of neutron-rich fission fragment beams extracted from thick targets irradiated by fast neutrons.