111025016
Single bunch intensity monitoring system using an improved wall current monitor
The length and intensity of individual beam bunches are important parameters in collider operations. A system for automatically measuring these parameters has been developed using a wall current monitor signal digitized by a 1 GHz sampling oscilloscope under microprocessor control. Bunch length and intensity are computed by the microprocessor and presented to the host computer. To verify the accuracy required, attention was given to the system's calibration and frequency response. The system has been successfully used to monitor colliding beam operations at Fermilab. The current 5% accuracy in measuring single-bunch intensity demonstrates the excellent fidelity and bandwidth of the system. The design of a resistive wall monitor with 3 kHz to 6 GHz bandwidth and less than 1 dB amplitude variation is presented. Using a microwave absorber inside the vacuum chamber to reduce noise is discussed.<<ETX>>
35394655
Magnetic field measurements of Fermilab main injector dipoles
Measurements of the Fermilab Main Injector dipoles using a partially redundant system of integrated and point measurements were carried out for quality assurance. Additional special measurements studied the hysteretic field strength. Results from these measurements are presented.
54609000
Strength and shape of the magnetic field of the Fermilab Main Injector dipoles
Measurements of 230 6-meter and 136 4-meter dipoles constructed for the Fermilab Main Injector were carried out as part of the magnet production effort. An automated measurement system provided data on magnetic field strength and shape using several partially redundant systems. Results of these measurements are available for each individual magnet for use in accelerator modelling. In this report we will summarise the results on all of the magnets to characterise the properties which will govern accelerator operation.
120282931
Fermilab Main Injector commissioning status
The Fermilab Main Injector construction project is nearing completion. The commissioning of the Main Injector began in late 1998. The status of the beam studies and fulfilment of the project commissioning milestones is presented.
123199387
Design of the Fermilab Main Injector Lambertson
A common design has been adopted for a high field (1.1 T) Lambertson magnet for use in the four injection/extraction channels of the Main Injector (MI) as well as the Tevatron injection channel. To support the extraction/injection of 150 GeV/c protons and pbars, the field within the "field region" of the Lambertson should reach 1.1 Tesla with less than 0.3% variation in a 2 by 12 inch good field aperture. Utilization for the 8.9 GeV/c pbars and resonant extraction of 120 GeV/c protons place stringent aperture requirements on the magnet design. In addition, this magnet must simultaneously support circulating beam in the energy range of 8.9 GeV/c to 900 GeV/c, through its "field free" region. At maximum excitation, the leakage field in this region must be kept to a minimum to avoid any deleterious effects on the circulating beam. The magnet design parameters which meet the aperture, magnetic, and structural requirements as well as the selection criteria of the steel are discussed.
122534152
Doubler system quench detection threshold
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.
14737332
The SUGRA Quintessence Model Coupled to the MSSM
We study the cosmological evolution of the universe when quintessence is modeled within supergravity, supersymmetry is broken in a hidden sector, and we also include observable matter in a third independent sector. We find that the presence of hidden sector supersymmetry breaking leads to modifications of the quintessence potential. We focus on the coupling of the SUGRA quintessence model to the MSSM and investigate two possibilities. First one can preserve the form of the SUGRA potential provided the hidden sector dynamics is tuned. The currently available limits on the violations of the equivalence principle imply a universal bound on the vacuum expectation value of the quintessence field now, \kappa ^{1/2}Q\ll 1. On the other hand, the hidden sector fields may be stabilised leading to a minimum of the quintessence potential where the quintessence field acquires a mass of the order of the gravitino mass, large enough to circumvent possible gravitational problems. However, the cosmological evolution of the quintessence field is affected by the presence of the minimum of the potential. The quintessence field settles down at the bottom of the potential very early in the history of the universe. Both at the background and the perturbation levels, the subsequent effect of the quintessence field is undistinguishable from a pure cosmological constant