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Microwave surface resistance measurements were made on large-area (11.4-cm/sup 2/) Tl-Ba-Ca-Cu-O thick films/ss ( approximately 10 mu m) which were magnetron sputtered onto oriented Ag alloy (Consil 995) substrates. Initial films were prepared by depositing a BaF/sub 2/ buffer layer between the superconducting film and the substrate to control the film/substrate interaction; however, films exhibiting the best microwave properties were prepared without a buffer layer. Surface resistance measurements were made by replacing the end wall of an 18-GHz Cu cavity (TE/sub 011/ mode) with the superconducting film. The best surface resistance values obtained on the unbuffered film were 4 and 14 m Omega at 10 K and 77 K, respectively; the corresponding Cu values are 8 m Omega and 21 m Omega . The dependence of surface resistance on surface magnetic field was measured in a similar way except that an Nb cavity was used instead of a Cu one. Films exhibiting the highest degree of c-axis texturing show the weakest dependence of surface resistance on magnetic field and also exhibit the sharpest high-frequency transition into the superconducting state. These results are important for potential cavity applications of these materials.

Microwave surface resistance measurements have been made on large-area Ti-Ba-Ca-Cu-O thick films magnetron-sputtered onto oriented Ag alloy substrates by replacing the end wall of an 18 GHz TE/sub 011/ mode Cu cavity with the superconducting film. The best surface resistance values obtained are 4 and 14 m Omega at 10 K and 77 K, respectively; corresponding Cu values are 8 and 21 m Omega . The dependence of the surface resistance on microwave power was measured in a similar way except that a Nb cavity was used instead of a Cu cavity. Typically, the surface resistance of the film begins to rise in 1-10 Oe of microwave field and saturates in 20-60 Oe. A model is presented relating the observed saturation to critical penetration of Josephson junctions. Films exhibiting the highest degree of c-axis texturing show the weakest dependence of surface resistance on power and also exhibit the sharpest transition to the superconducting state as measured at high frequency. >

An increase by over three orders of magnitude from 0.58 mΩ to 1.17 Ω was observed at 4.0 K in the 3 GHz microwave surface resistance of ceramic YBa2Cu3O7−δ following exposure to neutrons. The transport resistivity of an unirradiated pellet was linear in temperature down to Tc with a room‐temperature value of 2.13 mΩ cm and a resistivity extrapolated to 4.0 K of 0.53 mΩ cm. Following irradiation, the resistivity rose with decreasing temperature from a room‐temperature value of 1.5 Ω cm to a maximum at around 45 K with little change evident at Tc . These results, in conjunction with eddy current, susceptibility, iodometric titration, and thermally stimulated luminescence measurements on irradiated and unirradiated samples, collectively suggest that the effect of neutron irradiation has been to decrease intergranular coupling without the development of an insulating phase.

Surface resistance measurements on Tl‐Ba‐Ca‐Cu‐O thick films (∼15 μm) magnetron sputtered onto BaF2‐buffered, silver‐based (Consil 995) substrates have been made at a microwave frequency of 22 GHz. The relatively large‐area films (∼5 cm2) are characterized by surface resistance values of 6.9±2 mΩ at 11.3 K and 30.2±1 mΩ at 77 K; the corresponding values for Cu are 10 and 22 mΩ, respectively. These results demonstrate that Tl‐Ba‐Ca‐Cu‐O can be deposited onto large‐area, metallic substrates with characteristic surface resistance values lower than Cu at 4 K. Orientation of the film should improve the surface resistance at 77 K, thereby making the fabrication of microwave cavities that are superior to Cu possible.

Measurements are presented of the transverse properties of the booster synchrotron. The principal transverse limitations to operational performance have been due to restricted aperture and improper multiturn injection. In addition to these features, working point, chromaticities, high-intensity effects, and injection matching are discussed.

The first three months of operation of the NAL linac after first achieving a 200-MeV beam have been encouraging. The design performance has been achieved at beam intensities of about 20 mA both in the transverse emittance and the momentum spread. Attempts have not been made to go to intensities of 100 mA or greater as yet, and it will be interesting to see how the beam quality is affected by intensity. It is expected that when the linac rf phase and amplitude controls are properly working, the beam quality will be less than the design values. In particular, the momentum spread at the present operating currents is sufficiently small so that a debunching cavity currently is not envisioned. The beam measurements made so far confirm the theoretical results obtained with the PARMILA dynamics program. The particle distributions used in the program are those measured at the entrance to the linac. The large number of components in the systems have lead to concern over the reliability of the linac. The performance over the last three months has dispelled some of this concern. As running periods have increased the failure rate has decreased. Only two major problems stand out at this time. The first is the failure of the spring contacts on the filament leads to the power amplifier tubes. Installation care and the elimination of two of the contact rings which were not water-cooled seem to be providing at least a temporary solution.

A free-electron laser (FEL) oscillator, driven by an rf linac, requires a train of electron bunches delivered to an undulator. The electron-beam brightness requirement exceeds that available from a conventional buncher. The demonstrated high peak brightness of laser-illuminated photoemitters indicates that the conventional buncher system might be eliminated entirely without the usual large loss in beam brightness that occurs in bunchers. A photoemitter with a current density of about 200 A/cm2 is located on an end wall of an rf cavity to accelerate a 60-ps bunch of electrons to 1 MeV as rapidly as possible. Preliminary experimental work and simulation calculations are presented.

This paper gives construction details of the dipole and quadrupole magnets, a brief description of the proton injection line, and a short report of the vacuum system design for the existing Fermilab Cooling Ring.

We recently demonstrated that insulating surface impurity phases in high‐temperature superconductors can be detected by thermally stimulated luminescence. Moreover, we suggested that the intensity of luminescence is related to the magnitude of the rf surface resistance. In this work we show that a quantitative correlation exists between these two quantities, and that luminescence can be a very useful technique for estimating rf surface resistance.

During adiabatic capture and initial 30 MHz beam bunching in the Fermilab Booster very high frequency structure is observed on the bunches. The structure has the appearance of a bunch shape oscillation instability which appears and disappears in a sporadic manner. A computer simulation of injection dynamics reveals the fact that the observed structure is related to re-appearance of the injected linac bunch structure after relocation within the booster phase space.

It has recently been suggested1 that the present high energy synchrotrons at CERN and Fermilab could be operated as pp storage rings with a center-of-mass energy of some 800 GeV. The Fermilab Energy Doubler/Saver, in addition, would be quite suitable as a high performance storage ring, producing collisions at 2 TeV in the center-of-mass. In order to achieve useful luminosity it is necessary to: 1) collect antiprotons from ˜-80 GeV protons colliding on a stationary target, 2) cool the phase space of the initially diffuse p's, and 3) accumulate the cooled p's over cycles. Several methods have been devised to carry out this repetitive accumulation and cooling. 2,3,4

The intensity of the Fermilab booster accelerator has been limited in part by longitudinal effects. These include longitudinal space charge blowup prior to RF capture, phase space dilution during capture and insufficient voltage to provide bucket area to accelerate the diluted beam. Measurements of beam properties under these conditions, as well as high intensity effects during acceleration, are presented.

At present there are two working injection methods; single-turn using a ferrite kicker magnet and multiturn using a pulsed set of 4 dipoles in one straight section. The operating characteristics of these methods are described. The expected implementation of H injection will involve the incorporation of devices for all three methods in one 6-m long straight section. The H-scheme is described and the expected operating characteristics compared to the present methods.

The "cooling" of protons by electrons has been studied by the accelerator group at the Institute of Nuclear Physics at Novosibirsk, U.S.S.R.l. They have achieved damping of proton-betatron oscillations by Coulomb interactions with "cold" electrons as described by simple theory. They also observe fast damping when the longitudinal velocities of all the protons and electrons are very nearly the same and the electrons are trapped in a longitudinal magnetic field. This effect results from the extended interaction between the same electrons and protons.

Successful electron cooling of antiproton beams requires a precisely aligned and high quality electron beam. Mean e- momentum and energy are to be held within 0.25 mrad and ? eV respactively. In addition the e- "temperature" about this mean (rest frame velocity spread) should be held to ?? eV. The diagnostics required to align the beam in angle and energy are rather straightforward. The temperature measuring diagnostics (one for T?; one for T?) are more exotic.