On possible lower bounds for the direct detection rate of SUSY Dark Matter

One can expect accessible lower bounds for dark matter detection rate due to restrictions on masses of the SUSY-partners. To explore this correlation one needs a new-generation large-mass detector. The absolute lower bound for detection rate can naturally be due to spin-dependent interaction. Aimed at detecting dark matter with sensitivity higher than $10^{-5}$ event/day/kg an experiment should have a non-zero-spin target. Perhaps, the best is to create a GENIUS-like detector with both Ge-73 (high spin) and Ge-76 nuclei.Comment: latex, 5 pages, 3 figures. Talk given at the III International Conference on Non-accelerator New Physics (NANP'01), Dubna, 19--23 June, 200

High dynamic range beam profile measurements

In future high intensity, high energy accelerators, beam loss has to be minimized to maximize performance and reduce activation of accelerator components. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation and to have the possibility to test available theoretical models with an adequate experimental setup. Measurements based on optical transition radiation (OTR) provide an interesting opportunity for high resolution measurements of the transverse beam profile. In order to be applicable for measurements within the beam halo region, it is of utmost importance that a high dynamic range is covered by the image acquisition system. The existing camera system as it is installed in the CLIC Test Facility (CTF3) is compared to a step-by-step measurement with a photo multiplier tube (PMT) and measurements with a cooled charge injection device (CID) camera. The latter acquisition technique provides an innovative and highly flexible approach to high dynamic range measurements and is presented in some detail

MOSFET dosimetry for microbeam radiation therapy at the European Synchrotron Radiation Facility

Preclinical experiments are carried out with ~20–30 μm wide, ~10 mm high parallel microbeams of hard, broad-‘‘white’’-spectrum x rays (~50–600 keV) to investigate microbeam radiation therapy (MRT) of brain tumors in infants for whom other kinds of radiotherapy are inadequate and/or unsafe. Novel physical microdosimetry (implemented with MOSFET chips in the ‘‘edge-on’’ mode) and Monte Carlo computer-simulated dosimetry are described here for selected points in the peak and valley regions of a microbeam-irradiated tissue-equivalent phantom. Such microbeam irradiation causes minimal damage to normal tissues, possible because of rapid repair of their microscopic lesions. Radiation damage from an array of parallel microbeams tends to correlate with the range of peak-valley dose ratios (PVDR). This paper summarizes comparisons of our dosimetric MOSFET measurements with Monte Carlo calculations. Peak doses at depths \u3c22 mm are 18% less than Monte Carlo values, whereas those depths \u3e22 mm and valley doses at all depths investigated (2 mm–62 mm) are within 2–13% of the Monte Carlo values. These results lend credence to the use of MOSFET detector systems in edge-on mode for microplanar irradiation dosimetry

Investigations into beam monitors at the AE g ̄ gˉ\bar {g} IS experiment

Detailed diagnostic of antiproton beams at low energies is required for essentially all experiments at the Antiproton Decelerator (AD), but will be particularly important for the future Extra Low ENergy Antiproton ring (ELENA) and its keV beam lines to the different experiments. Many monitors have been successfully developed and operated at the AD, but in particular beam profile monitoring remains a challenge. A dedicated beam instrumentation and detector test stand has recently been setup at the AE g ̄ $\bar {g}$ IS experiment (Antimatter Experiment: Gravity, Interferometry, Spectroscopy). Located behind the actual experiment, it allows for parasitic use of the antiproton beam at different energies for testing and calibration. With the aim to explore and validate different candidate technologies for future low energy beam lines, as well as the downstream antihydrogen detector in AE g ̄ $\bar {g}$ IS, measurements have been carried out using Silicon strip and pixel detectors, a purpose-built secondary emission monitor and emulsions. Here, results from measurements and characterization of the different detector types with regard to their future use at the AD complex are presented

The CRESST Dark Matter Search

The current status of CRESST (Cryogenic Rare Event Search using Superconducting Thermometers) and new results concerning the detector development are presented. The basic technique of CRESST is to search for particle Dark Matter (WIMPS, Weakly Interacting Massive particles) by the measurement of non-thermal phonons as created by WIMP-induced nuclear recoils. Combined with the newly developed method of simultaneous measurement of scintillation light, strong background discrimination is possible, resulting in a substantial increase in WIMP detection sensitivity. The short and long term perspectives of CRESST are discussed.Comment: 12 pages, 6 figure

Optical diffraction radiation for position monitoring of charged particle beams

In the framework of the future linear collider collaboration (CLIC, ILC), non-intercepting beam monitoring instruments are under development for very low emittance and high charge density beams. Optical diffraction radiation (ODR) was studied and developed during the last years focussing on beam size measurements. We propose in the paper to consider the use of diffraction radiation for ultra relativistic beams as position monitors with applications for the centering of scrapers, collimators and targets with high resolution. We present the experimental results obtained using small aperture slits on the ATF2 extraction beam line at KEK and on the Cornell Electron Storage Ring with 1.2 GeV and 2.1 GeV electrons respectively

Evaluation of the LEP Centre-of-Mass Energy Above the W-Pair Production Threshold

Knowledge of the centre-of-mass energy at LEP2 is of primary importance to set the absolute energy scale for the measurement of the W-boson mass. The beam energy above 80 GeV is derived from continuous measurements of the magnetic bending field by 16 NMR probes situated in a number of the LEP dipoles. The relationship between the fields measured by the probes and the beam energy is calibrated against precise measurements of the average beam energy between 41 and 55 GeV made using the resonant depolarisation technique. The linearity of the relationship is tested by comparing the fields measured by the probes with the total bending field measured by a flux loop. This test results in the largest contribution to the systematic uncertainty. Several further corrections are applied to derive the the centre-of-mass energies at each interaction point. In addition the centre-of-mass energy spread is evaluated. The beam energy has been determined with a precision of 25 MeV for the data taken in 1997, corresponding to a relative precision of 2.7x10^{-4}. This is small in comparison to the present uncertainty on the W mass measurement at LEP. However, the ultimate statistical precision on the W mass with the full LEP2 data sample should be around 25 MeV, and a smaller uncertainty on the beam energy is desirable. Prospects for improvements are outlined.Comment: 24 pages, 10 figures, Latex, epsfig; replaced by version accepted by European Physical Journal

Recent Results on Energy Calibration at LEP

The determination of the centre-of-mass energy at the four experiments installed on the CERN Large Electron Positron (LEP) collider is one of the major ingredients in the Standard Model investigations being carried on in the context of the experimental programme. Several depolarising effects at beam energies beyond 60 GeV limit the application of the Resonant Depolarisation (RD) method, which provi des an energy uncertainty of about ±1 MeV at the Z0 resonance. Extrapolation techniques from magnetic field measurements are used to obtain beam energies in the W-pair region, aiming at a total energy error £15 MeV. Consistency checks over a large range of precisely calibrated energies are mandatory to contain systematic errors from extrapolation. Progress obtained in extending the polarisable ener gy range in the 1997 LEP Run and the preliminary extrapolation errors are reported

Event categories in the EDELWEISS WIMP search experiment

Four categories of events have been identified in the EDELWEISS-I dark matter experiment using germanium cryogenic detectors measuring simultaneously charge and heat signals. These categories of events are interpreted as electron and nuclear interactions occurring in the volume of the detector, and electron and nuclear interactions occurring close to the surface of the detectors(10-20 mu-m of the surface). We discuss the hypothesis that low energy surface nuclear recoils,which seem to have been unnoticed by previous WIMP searches, may provide an interpretation of the anomalous events recorded by the UKDMC and Saclay NaI experiments. The present analysis points to the necessity of taking into account surface nuclear and electron recoil interactions for a reliable estimate of background rejection factors.Comment: 11 pages, submitted to Phys. Lett.