The OLYMPUS experiment Milner, R.; Hasell, D.K.; Kohl, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2014, Letnik:
741
Journal Article
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Odprti dostop
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, μpGEp/GMp, made using polarization techniques and those made in unpolarized experiments. OLYMPUS operated on the DORIS storage ring at DESY, alternating between 2.01GeV 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°–75°. Symmetric Møller/Bhabha calorimeters at 1.29° and telescopes of GEM and MWPC detectors at 12° served as luminosity monitors. A total luminosity of approximately 4.5fb−1 was collected over two running periods in 2012. This paper provides details on the accelerator, target, detectors, and operation of the experiment.
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.
A forward silicon strip system for the ATLAS HL-LHC upgrade Aliev, M.; Ariza, D.; Barber, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
730
Journal Article
Recenzirano
Odprti dostop
In the year 2022 an upgrade of the Large Hadron Collider (LHC) is planned to increase the luminosity such that an integrated luminosity of Lint∼3000fb−1 can be accumulated by 2030 1. The radiation ...damage of the present inner tracker at this date and the high track density of the High Luminosity LHC (HL-LHC) require an upgrade of the inner tracker of the ATLAS (A Toroidal LHC ApparatuS) experiment. A new integration concept will be used: the readout electronics is directly glued on the strip surface of the silicon sensors and the sensors are glued to a support structure. For the barrel region this structure is referred to as a Stave and for the end-cap region it is referred to as a Petal. For tests a smaller version, the Petalet, will be build with two design concepts. In this article the construction method is explained and first hybrid test results for one Petalet sensor are presented.
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.
Summary
Life cycle greenhouse gas (LC‐GHG) emissions from electricity generated by a specific resource, such as gas and oil, are commonly reported on a country‐by‐country basis. Estimation of ...variability in LC‐GHG emissions of individual power plants can, however, be particularly useful to evaluate or identify appropriate environmental policy measures. Here, we developed a regression model to predict LC‐GHG emissions per kilowatt‐hour (kWh) of electricity produced by individual gas‐ and oil‐fired power plants across the world. The regression model uses power plant characteristics as predictors, including capacity, age, fuel type (fuel oil or natural gas), and technology type (single or combined cycle) of the plant. The predictive power of the model was relatively high (R2 = 81% for predictions). Fuel and technology type were identified as the most important predictors. Estimated emission factors ranged from 0.45 to 1.16 kilograms carbon dioxide equivalents per kilowatt‐hour (kg CO2‐eq/kWh) and were clearly different between natural gas combined cycle (0.45 to 0.57 kg CO2‐eq/kWh), natural gas single cycle (0.66 to 0.85 kg CO2‐eq/kWh), oil combined cycle power plants (0.63 to 0.79 kg CO2‐eq/kWh), and oil single cycle (0.94 to 1.16 kg CO2‐eq/kWh). Our results thus indicate that emission data averaged by fuel and technology type can be profitably used to estimate the emissions of individual plants.
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