We describe a technique of obtaining radioactive
99m
Tc isotope by irradiation of molybdenum with high-intensity beam of bremsstrahlung photons from the electron beam of the linear electron ...accelerator (LUE50) of the Alikhanyan National Science Laboratory (ANSL, former Yerevan Physics Institute). We have elaborated and created an experimental plant for development of
99m
Tc production technology. Upgrading of linac has been performed aimed at raising the beam intensity and density. A system of automated control of the parameters of the plant and accelerator was built up. We carried out preliminary studies of
99m
Tc obtaining technique and give quantitative and qualitative results.
Phys. Rev. Lett. 126, 162501 (2021) We report the first measurement of the average of the electron-proton and
positron-proton elastic scattering cross sections. This lepton charge-averaged
cross ...section is insensitive to the leading effects of hard two-photon
exchange, giving more robust access to the proton's electromagnetic form
factors. The cross section was extracted from data taken by the OLYMPUS
experiment at DESY, in which alternating stored electron and positron beams
were scattered from a windowless gaseous hydrogen target. Elastic scattering
events were identified from the coincident detection of the scattered lepton
and recoil proton in a large-acceptance toroidal spectrometer. The luminosity
was determined from the rates of M{\o}ller, Bhabha and elastic scattering in
forward electromagnetic calorimeters. The data provide some selectivity between
existing form factor global fits and will provide valuable constraints to
future fits.
We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading ...effects of hard two-photon exchange, giving more robust access to the proton's electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of Møller, Bhabha and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits.
The OLYMPUS collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, \(R_{2\gamma}\), a direct measure of the contribution of hard ...two-photon exchange to the elastic cross section. In the OLYMPUS measurement, 2.01~GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of \(\approx 20\degree\) to \(80\degree\). The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved GEM and MWPC detectors at \(12\degree\), as well as symmetric Møller/Bhabha calorimeters at \(1.29\degree\). A total integrated luminosity of 4.5~fb\(^{-1}\) was collected. In the extraction of \(R_{2\gamma}\), radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of \(R_{2\gamma}\), presented here for a wide range of virtual photon polarization \(0.456<\epsilon<0.978\), are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.
Nuclear Inst. and Methods in Physics Research, A (2014) pp. 1-17 The OLYMPUS experiment was designed to measure the ratio between the
positron-proton and electron-proton elastic scattering cross ...sections, with the
goal of determining the contribution of two-photon exchange to the elastic
cross section. Two-photon exchange might resolve the discrepancy between
measurements of the proton form factor ratio, $\mu_p G^p_E/G^p_M$, made using
polarization techniques and those made in unpolarized experiments. OLYMPUS
operated on the DORIS storage ring at DESY, alternating between 2.01~GeV
electron and positron beams incident on an internal hydrogen gas target. The
experiment used a toroidal magnetic spectrometer instrumented with drift
chambers and time-of-flight detectors to measure rates for elastic scattering
over the polar angular range of approximately $25^\circ$--$75^\circ$. Symmetric
M{\o}ller/Bhabha calorimeters at $1.29^\circ$ and telescopes of GEM and MWPC
detectors at $12^\circ$ served as luminosity monitors. A total luminosity of
approximately 4.5~fb$^{-1}$ was collected over two running periods in 2012.
This paper provides details on the accelerator, target, detectors, and
operation of the experiment.
Measurements are presented of inclusive charm and beauty cross sections in e(+)p collisions at HERA for values of photon virtuality Q(2) > 150 GeV2 and of inelasticity 0.1 < y < 0.7. The charm and ...beauty fractions are determined using a method based on the impact parameter, in the transverse plane, of tracks to the primary vertex, as measured by the H1 vertex detector. The data are divided into four regions in Q(2) and Bjorken x, and values for the structure functions F-2(c (c) over bar) and F-2(b (b) over bar) are obtained. The results are found to be compatible with the predictions of perturbative quantum chromodynamics.
A measurement of charm and beauty photoproduction at the electron proton collider HERA is presented based on the simultaneous detection of a D*(+/-) meson and a muon. The correlation between the D* ...meson and the muon serves to separate the charm and beauty contributions and the analysis provides comparable sensitivity to both. The total and differential experimental cross sections are compared to LO and NLO QCD calculations. The measured charm cross section is in good agreement with QCD predictions including higher order effects while the beauty cross section is higher.
The proton structure function F-2(x, Q(2)) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range ...of very low virtualities of the exchanged photon, Q(2), down to 0.5 GeV2, and Bjorken x up to similar to 0.06, a region which has not been covered previously by inclusive measurements at HERA. The results are in agreement with the measurements from fixed target lepton-nucleon scattering experiments. (C) 2004 Published by Elsevier B.V.
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