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Sheep keds ( Melophagus ovinus (L.)), an obligate external parasite of economic concern, are a continual problem in high-elevation grazing situations in most temperate sheep production areas of the world. The influence of sheep breed, age, and the interaction of breed*age on host-parasite ecology, could inform integrated keds management strategies. We measured ked density and presence/absence on Rambouillet, Hampshire, and Suffolk ewes in Wyoming, USA to determine the role of breed, ewe age, and breed*age interaction on ked parasitism. Eighteen ewes per breed group were examined for ked presence and ked density with sub-groups within each breed of 1, 2, and 3+ years of age. We used a generalized linear mixed model (GLMM) to analyze the effect of breed, age, and the interaction of breed and age, on a stacked response variable ‘ked infestation’ that is a function of both ked presence and density. Ked infestations differed by ewe age ( p =0.0153; F =4.55) and by ewe breed ( p =0.0178; F =3.30). Ked infestation increased with ewe age, as 29% of yearling ewes had keds and 63% of three-year old ewes had keds. Ked infestation was the greatest on the fine-wool Rambouillet ewes (72% presence; 1.4 keds per ewe), and was lower on the medium-wool breeds (Hampshire ewes had 39% presence and 1.0 keds per ewe and Suffolk ewes had 22% presence and 0.3 keds per ewe). The breed*age interaction did not significantly influence ked infestation in our joint model of the stacked bivariate ked infestation response outcome ( p =0.1292; F =1.75). The lack of a significant interaction is attributed to the relatively large variance around the mean for such small breed-age sub-groups and warrants additional study. Our results have implications for parasite management as 100% of three-year old Rambouillet ewes had keds present, but none of the yearling Suffolk ewes had any keds and only 29% of three-year old Suffolk ewes had keds present. The results from our study indicate keds do discriminate by breed perhaps due to an ecological adaptation for a wool-environment that is dense and comprised of a long staple – features characteristic of the Rambouillet ewes in our study. Integrated ked management strategies could manipulate this host-parasite ecology by selecting resistant breeds and/or strategically treating the most susceptible ewes. For example, this could be all Rambouillet ewe ages or only Suffolk ewes >2 years of age.

In order to demonstrate the potential power of maternal effects on litter size and growth in pigs a reciprocal cross of Berlin Miniature Pigs and Durocs was carried out. The average body weight of the Duroc dams (151 kg) was more than three times higher than the weight of the Miniature Pig dams (48 kg). A considerable maternal effect on fertility, estimated from reciprocal crossbred differences in the litter size of 3.5 piglets was found. The least Squares means of birth weight were 1.18 kg and 0.75 kg for Fl animals bom from Duroc dams and Miniature Pig dams, respectively. This maternal caused disadvantage in body weight of crossbred offspring from Miniature Pig dams is compensated in the interval from weaning to the 13th week of age. The end weight estimated by means of Gompertz and Bertalanffy growth functions showed only minor differences between the reciprocal crossed groups in favour of Fl born from Duroc dams. Our data suggest that the uterine capacity of the dam could play an important role in the fertility of extreme breed crosses. Concerning growth performance the milk yield of the sow and the influence of the birthweight of the piglets were discussed.

The following steps were performed to analyse heterosis and QTL effects in litter size of mice: intercross of mouse inbred strains C57BL/6J and Balb/cJ in order to produce a F2 generation with 948 female animals; selection of trait groups with extreme high ((13 offspring) and extreme low litter size (5 offspring)); typing of 56 microsatellites with an average distance of 32 cM; detection of different chromosome regions with associations to heterosis in litter size. Chromosome 19 was associated to heterosis in litter size. Additional animals with extreme high and low litter sizes were then typed for four DNA markers on chromosome 19 and used for QTL mapping. A QTL was identified for litter size in segment D19Mit28 &ndash: D19Mit99 with a maximum at 15 cM (p ≤ 0.05). The QTL explains about 11% of the phenotypic variance in the F2 generation. With a degree of dominance of 4.09 the QTL shows that superdominance can explain heterosis in litter size.

The final phase of the Fermilab upgrade proposal calls for a new ring of superconducting magnets to be placed in the existing main accelerator tunnel. The goal of this design study is to specify a high field dipole (HFD) that is capable of supporting fixed target operation (ramping, resonant extraction) at a field of 6.6 T (1.5 TeV) and colliding beam physics at 8.0 T (1.8 TeV). The magnetic field quality at high field is set by the large amplitude orbits associated with resonant extraction. The fixed quality must therefore be at least as good as the existing Tevatron magnets which fulfil these criteria. The high fields and large aperture of this magnet result in large forces on the coil and collar assemblies. Therefore, the cold mass design must be able to sustain these forces while providing sufficient cooling to the coils during 4.2-K fixed target operation, and a minimum heat load during 1.8-K collider operation. >

A new low beta insertion has been designed for the B0 and D0 straight sections of the Tevatron Collider. Each low beta insertion consists of 18 superconducting quadrupoles which are powered independently of the Tevatron accelerator magnets to focus the beams at the interaction region. The authors describe the quench behavior of the low beta quadrupoles, their power circuits, and their quench protection systems. >

In order to increase the usable accelerating gradient in Superconducting TESLA cavities, the field emission threshold barrier must be raised. As has been previously demonstrated on S-Band cavities, a way to accomplish this is with the use of high peak power RF processing. A transmitter with a peak power of 2 MWatt and 300 /spl mu/sec pulse length has been assembled and has been used to process TESLA cavities. Several five cell TESLA cavities at 1.3 GHz have been manufactured for this purpose. This transmitter and the cavities will be described and the results of the tests will be presented. >

New low- beta insertions will be used in the Tevatron collider at both the B0 and D0 interaction regions. To reduce the beam-beam tune shift, electrostatic separators will be installed to separate the beams horizontally and vertically at all but the two interaction points. An insertion has been installed at the B0 straight section and enough separators to create collisions at B0 only. The initial beam tests using these devices are described. The procedures for tuning of the insertion and separators are described. Also discussed is the procedure to change the lattice from the injection lattice to the 50-cm beta lattice used in high energy physics. >

Construction and testing of the components for the new Tevatron D0/B0 low beta insertion are nearly complete. The devices include superconducting cold iron quadrupoles utilizing a two-shell, cos2 theta coil geometry with a 7.6-cm aperture. The maximum design gradient is 1.41 T/cm at an operating current of 4832 A. They have the highest current density with the highest peak field on the winding of any quadrupole yet built. The authors summarize the quench performance and ramp rate sensitivity of the two-shell design and relate the performance characteristics to the relevant aspects of design and fabrication. >

Results from the experimental testing of the prototype TESLA Test Facility (TTF) RF photoinjector are summarized. Preliminary measurements of the performance of the injector indicate that, with refinement, the design values for the transverse emittances (20/spl times/20 /spl pi/ mm-mr) are not unrealistic, with uncompressed transverse emittances of 40 /spl pi/ mm-mr having been obtained under somewhat less ideal circumstances than those simulated. Preliminary pulse length measurements with and without the pulse compressor suggest pulse compression, but further study is required.

An electron photo-injector facility has been constructed at Fermilab for the purpose of providing a 14-18 MeV electron beam with high charge per bunch (8 nC), short bunch length (1 mm RMS), and small transverse emittance. The facility was used to commission a second-generation photo-cathode RF gun for the TESLA Test Facility (TTF) Linac at DESY; in the future, the Fermilab electron beam will be used for R and D in bunch length compression, beam diagnostics, and new acceleration techniques. Acceleration beyond 4 MeV is provided by a 9-cell superconducting cavity. The cavity also provides a longitudinal position-momentum correlation for subsequent bunch length compression. We report on the RF tests and a first beam test of this cavity.

An RF photo-injector was installed at Fermilab between January and June 97. The photo-injector produced its first beam on 4 June 97. This report provides a brief description of the accelerator and a summary of the experiments carried out through December '97.

A collaboration has been formed between FNAL, UCLA, LNFN Milano, the University of Rochester, and DESY to develop the technology of an RF photoinjector, followed by a superconducting cavity, to produce high bunch charge (8 nC) with low normalized emittance (

RF input couplers for the superconducting cavities of the TESLA are under development at DESY and Fermilab. The coaxial part of the Fermilab input coupler has been tested up to 1.7 MW at Fermilab using 805 MHz rf power source. The test results, procedure and test setup are described.

A tremendous amount of work has been done over the course of the past several years on the design of dipole magnets for the SSC main collider. Although they dominate the total magnet cost for the project and thus deserve the tremendous research and development effort they have received, the main ring magnets represent only part of the magnet requirements for the SSC. This paper presents the work to date on the design of dipole magnets for the SSC high energy booster (HEB). A complete discussion of the design is beyond the scope of this work.1 Rather it serves as an overview of the main aspects of the complete design.

Tests have been completed on three prototype magnets and two production magnets to be used for the Tevatron DO/BO low-β insertion. These cold iron, two shell quadrupoles are made of 36 strand Rutherford type NbTi superconducting cable. Magnet field gradients well in excess of the design 1.41 T/cm have been achieved at a transfer function of 0.291 T/cm/kA. Quench performance at 4.2 K and 3.7 K and magnetic multipole measurement data are presented and discussed.

During the last year, the Fermilab Doubler magnets have benefited from a development effort to upgrade the performance of the superconducting magnets. This paper presents the results of this effort. The design philosophy and the fabrication techniques used on current magnets will be discussed, along with innovative laminated tooling which has been designed to give Fermilab a two dipole a day production capability. Specific topics to be discussed are coil geometry, coil winding techniques, coil clamp collars, buss geometry and insulation, integral quench heaters for quench protection, coil twist, coil helium irrigation and assembly techniques that assure azimuthal preload and accurate coil size.

The experimental study leading to the determination of the sensitivity needed for protecting the Fermilab Doubler from damage during quenches is presented. The quench voltage thresholds involved were obtained from measurements made on Doubler cable of resistance × temperature and voltage × time during quenches under several currents and from data collected during operation of the Doubler Quench Protection System as implemented in the B-12 string of 20 magnets. At 4kA, a quench voltage threshold in excess of 5.0V will limit the peak Doubler cable temperature to 452K for quenches originating in the magnet coils whereas a threshold of 0.5V is required for quenches originating outside of coils.

During the last few months, several full size prototype dipole magnets for the Fermilab Energy Doubler were successfully tested. This was the result of several concurrent programs in conductor development as well as magnet construction, production, and testing. The present magnets have achieved their design goal. Progress to this point has solved many pitfalls. A description is given of the present technology as well as some of the decisions that led to the present design.

Results are presented from tests of the third full-scale development dipole magnet for the Superconducting Super Collider (SSC) and from a retest of a 4.5-m model magnet of the same design mounted in an SSC cryostat. The 4.5-m magnet showed consistent quench performance between its original tests in boiling liquid helium in a vertical dewar and the current tests in forced-flow helium in a horizontal cryostat. Little or no retraining was observed over several thermal cycles. The full-length magnet required 12 quenches to train to its short-sample limit of 6800 A and displayed a reasonably stable quench plateau following training. Data are presented on quench behavior as a function of current and temperature, and on azimuthal and longitudinal loading of the coil by the support structure. >

The measurement of conductor motion, caused by exciting a superconducting dipole magnet, is compared to the measured field quality.

A test facility has been constructed at the B12 location of the Fermilab main accelerator in order to test superconducting Doubler magnet strings under conditions similar to their final operating conditions while minimizing the interference to the ongoing 400 GeV program. Tests on the cryogenic, magnet and magnet power supply systems have been performed. In addition, a quench protection system has been tested that protects the magnets from damage due to a quench up to the full operating current of the Doubler.

A superconducting magnet system testing area has been constructed above ground at the B12 location of the Fermilab main accelerator which facilitates the testing and development of superconducting magnet systems prior to committing their design to the full scale production Of the Doubler accelerator. The test results and operating experience of this system will be reported.

A low beta insertion has been installed at the BO straight section of the Tevatron, the location of the Collider Detector Facility. The focus is achieved with four superconducting quadrupole doublets. The engineering design and performance of this system exclusive of beam behavior will be described including the magnets and their power supply, quench protection and cryogenic subsystems.

Over the past several years, Fermilab has been operating with a single turn proton abort system in both the superconducting Tevatron and the conventional Main Ring. The abort kicker power supply for this system discharges a lumped capacitance into the inductive magnet load, causing the beam to enter the abort channel. The characteristics of this current waveform are defined by the requirements of the machine operation. The standard fixed target running mode calls for 12 booster batches of beam which leaves a rotating gap in the beams of approx.1.8 ..mu..s. The current waveform is required to rise to 90% of I/sub max/ in this time to avoid beam loss from partially deflected beam. Aperture limitations in both the accelerator and the abort channel demand that the current in the magnets stays above this 90% I/sub max/ for the 21 ..mu..s needed to ensure all the beam has left the machine. The 25 mm displacement needed to cleanly enter the abort channel at 1 TeV corresponds to a maximum current in each of the 4 modules of approx.20 kA. Similar constraints are needed for the Main Ring and Tevatron antiproton abort systems. A unique feature of this design is the highmore » voltage, high current diode assembly used to clip the recharge of the capacitor bank. This allows the current to decay slowly with the L/R time constant of the magnet and diode series combination. Special attention is given to the diode characteristics needed for this passive switching element. Operational experience and proposed upgrades are given for the two operational systems. 2 refs., 4 figs., 1 tab.« less

The relative ease of protecting an SSC magnet following a quench and the implications of quench protection on magnet reliability and operation are necessary inputs in a rational magnet selection process. As it appears likely that the magnet selection will be made prior to full scale prototype testing, an alternative means is required to ascertain the surviveability of contending magnet types. This paper attempts to provide a basis for magnet selection by calculating the peak expected quench temperatures in the 3 T Design C magnet and the 6 T Design D magnet as a function of magnet length. A passive, ''cold diode'' protection system has been assumed. The relative merits of passive versus active protection systems have been discussed in a previous report. It is therefore assumed that - given the experience gained from the Tevatron system - that an active quench protection system can be employed to protect the magnets in the eventuality of unreliable cold diode function.

Results are presented from tests of the first full length prototype SSC dipole magnet. The cryogenic behavior of the magnet during a slow cooldown to 4.5K and a slow warmup to room temperature has been measured. Magnetic field quality was measured at currents up to 2000 A. Averaged over the body field all harmonics with the exception of b 2 and b 8 are at or within the tolerances specified by the SSC Central Design Group. (The values of b 2 and b 8 result from known design and construction defects which will be corrected in later magnets.) Using an NMR probe the average body field strength is measured to be 10.283 G/A with point to point variations on the order of one part in 1000. Data are presented on quench behavior of the magnet up to 3500 A (approximately 55% of full field) including longitudinal and transverse velocities for the first 250 msec of the quench.

Primary rf input couplers for the superconducting accelerating cavities of the TESLA electron linear accelerator test to be performed at DESY, Hamburg, Germany are under development at both DESY and Fermilab. The input couplers consist of a WR650 waveguide to coaxial line transition with an integral ceramic window, a coaxial connection to the superconducting accelerating cavity with a second ceramic window located at the liquid nitrogen heat intercept location, and bellows on both sides of the cold window to allow for cavity motion during cooldown, coupling adjustments and easier assembly. To permit in situ high peak power processing of the TESLA superconducting accelerating cavities, the input couplers are designed to transmit nominally 1 ms long, 1 MW peak, 1.3 GHz rf pulses from the WR650 waveguide at room temperature to the cavities at 1.8 K. The coaxial part of the Fermilab TESLA input coupler design has been tested up to 1.7 MW using the prototype 805 MHz rf source located at the A0 service building of the Tevatron. The rf source, the testing system and the test results are described. >

In order to improve the RF capture in PPA, calculations and experiments have been perfarmed with higher harmonic terms added to the accelerating voltage. Computer calculations of the synchrotron phase space acceptance, using the phase potential, have shown that by adding the second harmonic it should be possible to increase the acceptance of PPA at capture by a factor of 2. Since in PPA the acceptance increases with energy, second harmonic needs to be added only during the first part of the acceleration and a suitable voltage program for the RF has been calculated. Initial experiments with the second harmonic added during the first 300 microseconds of the acceleration cycle showed an intensity gain in excess of 50%. Although only described for PPA, the method can easily be adapted to other machines.