17683309
Parasitic energy loss in the LEP superconducting cavities
The energy loss of bunches in the LEP superconducting (SC) cavities has been determined by measuring the closed orbit as a function of current with the beam position monitors located at finite dispersion. This method has already been used in earlier experiments to determine the distribution of the longitudinal impedance of different parts of LEP. In the present experiment the energy loss in two straight sections, containing only SC cavities, was compared with that in sections having both copper cavities and SC cavities. The results confirm the impedance calculations for the two types of cavities. The accuracy of the measurements was considerably improved by determining simultaneously the orbits of bunches with different currents. At the same time with these beam-based impedance measurements, the power dissipation was observed directly by local temperature monitors in different elements: the inter-cavity bellows inside the cryostat, the warm intermodule bellows, and ferrite absorbers which were installed in two places to reduce the energy leaking out of cavities. These observations were correlated with the change of cryogenics power consumption, and showed an unexpected dependence of energy loss on beam energy.
62825805
THE CLIC MACHINE PROTECTION
INTRODUCTION The proposed Compact Linear Collider (CLIC) [1, 2] is based on a two-beam acceleration scheme. The energy of two high-intensity, low-energy drive beams is extracted and transferred to the two low-intensity, high-energy main beams. The machine protection has to cope with a wide variety of failures, from real-time failures (RF breakdowns, kicker misfiring), to slow equipment failures, to beam instabilities (caused by e.g. temperature drifts, slow ground motions). Due to the many different types of accelerator components and the beams of various characteristics throughout the entire complex, the CLIC machine protection is an extensive subject. The machine protection has the mission to protect the various machine components from damage caused by ill controlled beams. The severity of the damage is given by the financial impact of the damage and the reduction in the operational availability of the facility. The risk equivalent is given by the product of the fault rate and the impact of the fault (i.e. in statistical terms: risk is the expectation value of the fault impact). This concept is illustrated by some examples for downtime in Table 1.
115464633
Do We Understand the Luminosity Imbalance
107933425
First trial of BOM harmonic analysis
61569699
The RTC-a software support system for the control of the CERN SPS
The RTC (Run Time Coordinator) is described. It is a software support system designed for the SPS (Super Proton Synchrotron) control system to provide a run time environment for application software. It coordinates the execution of individual programs or processes and supervises the process control, i.e. process synchronization, interprocess communication, data transfer, and operator I/O (input/output). This supervision includes the control of processes distributed on a Unix-based network. A standard language independent data interface is part of the system. The system includes tools for data presentation, error logging, and contention resolution. Separating system-dependent features for the body of the application programs leads to high flexibility and simplifies the software development. The basic philosophy of the RTC is discussed and its implementation is described.<<ETX>>
54676169
Measurement of chromatic effects in LEP
The chromaticity produced by the insertions and the lattice of LEP is corrected in the FODO lattice of the arcs which has horizontal and vertical phase advances of 90/spl deg/ and 60/spl deg/ for the LEP optics presently used. This is done with two horizontal and three vertical sextupole families. To check this correction scheme the non-linear chromaticities have been measured by observing the betatron tunes as a function of RF-frequency, i.e. of momentum deviation. The differences between the results and the expected effects of the sextupoles are interpreted in terms of octupole and decapole components in the dipole magnets. To check the distribution around the ring of the chromaticities and their corrections the betatron phase advances have been measured as a function of momentum deviation. This was done by observing an excited betatron oscillation for 1024 turns in all beam position monitors for different RF-frequencies. The results clearly show the negative chromaticity produced in the straight sections and its correction in the arcs. The parasitic sextupole components are found to be spread uniformly in the arcs within the measurement errors. Under this condition one finds that they have a negligible effect on the dynamic aperture.
117804044
The Present Status of the Search for Quarks
121640423
Preliminary results in the search for fractionally charged particles by the magnetic levitation electrometer
Abstract The operation of the magnetic levitation electrometer suggested in ref. 1 is described. Measurements on the first five graphite grains (containing altogether ∼ 10 16 nucleons) exclude the presence of quarks in them; a future program of search for terrestrial quarks by this instrument is outlined.
124837005
SEARCH FOR QUARKS WITH THE FERROMAGNETIC LEVITATION ELECTROMETER
2407484
On the miracle of the Coleman–Glashow and other baryon mass formulas
Abstract Due to a new measurement of the Ξ0 mass, the Coleman–Glashow formula for the baryon octet e.m. masses (derived using unbroken flavor SU3) is satisfied to an extraordinary level of precision. The same unexpected precision exists for the Gell Mann–Okubo formula and for its octet-decuplet extension (G. Morpurgo, Phys. Rev. Lett. 68 (1992) 139). We show that the old question “why do they work so well?” is now answered by the general parametrization method.
120572247
The electric neutrality of matter: A summary
Abstract We summarize the results of our experiments on the electric neutrality of matter. The number of isolated quarks in steel is less than one in 3.7 mg, corresponding to less than one in 2.2 × 10 21 nucleons. The upper limit to the electron proton charge difference is (0.8 ± 0.8) 10 −21 e . The procedure to establish this upper limit is discussed in some detail. The above results are compared with those from other experiments.