Search results for "beam"
showing 10 items of 2126 documents
A single hologram technique for the determination of absolute retardations in holographic photoelasticity
1975
A method for the determination of the absolute retardations families in photoelasticity. The method, which use real-time holographic interferometry, requires only one hologram for the observation of the absolute retardations over the whole model. This is achieved by viewing in the reconstruction process the loaded model through a polarizer. Where the polarization direction is parallel to one of the principal stresses, only the corresponding family of absolute retardations is observed. As an example of application the absolute retardations and stresses in a deep beam centrally loaded are determined.
Detection system for forward emitted photons at the Experimental Storage Ring at GSI
2013
A single photon counting system has been developed for efficient detection of forward emitted fluorescence photons at the Experimental Storage Ring (ESR) at GSI. The system employs a movable parabolic mirror with a central slit that can be positioned around the ion beam and a selected low noise photomultiplier for detection of the collected photons. Compared to the previously used system of mirror segments installed inside the ESR the collection efficiency for forward-emitted photons is improved by more than a factor of 5. No adverse effects on the stored ion beam have been observed during operation besides a small drop in the ion current of about 5% during movement of the mirror into the b…
Photodetachment ofH−in the presence of a low-frequency laser field
1993
The photodetachment of a model one-electron ion simulating ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ in the presence of a low-frequency field is analyzed. Two different geometries are considered in order to get information on the effect of the ponderomotive energy shift \ensuremath{\Delta} on the photodetachment cross section. Our calculations suggest that a correspondence may be established between the ponderomotive shift and the photodetachment cross section, when the ejected electron may exchange only a few low-frequency photons. This is in qualitative agreement with recent experimental observations. When a large number of processes are open in which the detached electron may exchange low…
Electromagnetic Calorimeter for HADES Experiment
2014
Electromagnetic calorimeter (ECAL) is being developed to complement dilep- ton spectrometer HADES. ECAL will enable the HADES@FAIR experiment to mea- sure data on neutral meson production in heavy ion collisions at the energy range of 2-10 AGeV on the beam of future accelerator SIS100@FAIR. We will report results of the last beam test with quasi-monoenergetic photons carried out in MAMI facility at Jo- hannes Gutenberg Universitat Mainz.
The design of a cascaded 800 MeV normal conducting C.W. race track microtron
1976
Abstract A c.w. electron accelerator of 820 MeV maximum output energy at 100 μ A beam current is proposed to make possible a large variety of coincidence experiments with energy electrons and photons as a future possibility of new, interesting experiments. It consists of a preaccelerator and 3 cascaded race track microtons using normal conducting rf structures. The design of this accelerator, based on detailed computational investigations of its beam dynamics and some experimental studies, is communicated and partly discussed in this paper.
Possibility of identifying the photon source studying the photon parameters
2004
Sometimes it is important to know the kind of laser and also the nature of the active media where the photons are produced, mainly when the photon source is situated at long distance from the target, and you can have information, only from the photons. The authors considered many ways of theoretical and applied research, using models for different types of lasers. High-speed and high-accuracy applications in processing trend to increase in the field of some important applications like laser beam welding and laser beam cutting. Some time the source presents inconstant parameters, and so, the measurements must be made in a relative short interval of time. The study requires problems like: spa…
Monte Carlo calculation of beam quality correction factors for PTW cylindrical ionization chambers in photon beams.
2020
The beam quality correction factor k Q for megavoltage photon beams has been calculated for eight PTW (Freiburg, Germany) ionization chambers (Farmer chambers PTW30010, PTW30011, PTW30012, and PTW30013, Semiflex 3D chambers PTW31021, PTW31010, and PTW31013, and the PinPoint 3D chamber PTW31016). Simulations performed on the widely used NE-2571 ionization chamber have been used to benchmark the results. The Monte Carlo code PENELOPE/penEasy was used to calculate the absorbed dose to a point in water and the absorbed dose to the active air volume of the chambers for photon beams in the range 4 to 24 MV. Of the nine ionization chambers analysed, only five are included in the current version of…
Brachytherapy structural shielding calculations using Monte Carlo generated, monoenergetic data
2014
Purpose: To provide a method for calculating the transmission of any broad photon beam with a known energy spectrum in the range of 20–1090 keV, through concrete and lead, based on the superposition of corresponding monoenergetic data obtained from Monte Carlo simulation. Methods: MCNP5 was used to calculate broad photon beam transmission data through varying thickness of lead and concrete, for monoenergetic point sources of energy in the range pertinent to brachytherapy (20–1090 keV, in 10 keV intervals). The three parameter empirical model introduced byArcher et al. [“Diagnostic x-ray shielding design based on an empirical model of photon attenuation,” Health Phys. 44, 507–517 (1983)] was…
A new measurement of the neutron detection efficiency for the NaI Crystal Ball detector
2015
We report on a measurement of the neutron detection efficiency in NaI crystals in the Crystal Ball detector obtained from a study of single π0 photoproduction on deuterium using the tagged photon beam at the Mainz Microtron. The results were obtained up to a neutron energy of 400 MeV . They are compared to previous measurements made more than 15 years ago at the pion beam at the BNL AGS.
MuPix7 - A fast monolithic HV-CMOS pixel chip for Mu3e
2016
The MuPix7 chip is a monolithic HV-CMOS pixel chip, thinned down to 50 \mu m. It provides continuous self-triggered, non-shuttered readout at rates up to 30 Mhits/chip of 3x3 mm^2 active area and a pixel size of 103x80 \mu m^2. The hit efficiency depends on the chosen working point. Settings with a power consumption of 300 mW/cm^2 allow for a hit efficiency >99.5%. A time resolution of 14.2 ns (Gaussian sigma) is achieved. Latest results from 2016 test beam campaigns are shown.