We report the observation of shadowing between two optical transition radiation (OTR) sources from a 205 MeV electron beam. The total optical intensity is measured as a function of the distance d ...between the sources, covering the range 0<d<4L_{v}, where L_{v} is the formation length of the particles. Data show that the total optical intensity starts decreasing due to shadowing when d approaches L_{v} until it becomes undetectable for very short distances d/L_{v}→0. A model based solely on interference between the two OTR sources is in good agreement with experimental data. To the knowledge of the authors this is the first systematic experimental observation of shadowing in OTR.
The Target Absorbers for Neutrals (TANs) represent one of the most radioactive regions in the Large Hadron Collider. Seven 40cm long fused silica rods with different dopant specifications, ...manufactured by Heraeus, were irradiated in one of the TANs located around the ATLAS experiment by the Beam RAte of Neutrals (BRAN) detector group. This campaign took place during Run 2 p＋p data taking, which occurred between 2016 and 2018. This paper reports a complete characterization of optical transmission per unit length of irradiated fused silica materials as a function of wavelength (240 nm–1500 nm), dose (up to 18 MGy), and level of OH and H2 dopants introduced in the manufacturing process. The dose delivered to the rods was estimated using Monte Carlo simulations performed by the CERN FLUKA team.
The High-Luminosity target neutral beam absorber (TAXN) is the radiation absorber of the neutral particle debris generated at the beam collisions carried out in the ATLAS and CMS detectors at the ...Large Hadron Collider (LHC). The new absorber will protect the superconducting magnets from this radiation to prevent their quenching at a design luminosity of7.5×1034cm−2s−1. This article describes the mechanical design of the TAXN assembly and the recombination chamber together with the thermal computations performed for the water-cooling and bakeout system prepared for the engineering design review held in January, 2021. It takes into account the internal integration of the zero degree calorimeter and beam rate of neutrals luminosity detector as well as their physics case overview. In addition, it provides the beam aperture breakdown and the heat deposition expected in the absorber.
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 1.2GeV and 2.1GeV electrons respectively.
A noninvasive, compact laserwire system has been developed to measure the transverse emittance of an H− beam and has been demonstrated at the new LINAC4 injector for the LHC at CERN. Light from a low ...power, pulsed laser source is conveyed via fiber to collide with the H− beam, a fraction of which is neutralized and then intercepted by a downstream diamond detector. Scanning the focused laser across the H− beam and measuring the distribution of the photo-neutralized particles enables the transverse emittance to be reconstructed. The vertical phase-space distribution of a 3 MeV beam during LINAC4 commissioning has been measured by the laserwire and verified with a conventional slit and grid method.
Our previous studies have shown that lowering the dose of pegylated liposomal doxorubicin (PLD) and bortezomib in combination with intravenous dexamethasone on a longer 4-week cycle maintained ...efficacy and improved tolerability in both previously untreated and relapsed/refractory (R/R) multiple myeloma (MM) patients. Lenalidomide has shown efficacy in combination with bortezomib and dexamethasone but this combination has been poorly tolerated. We conducted this phase 2 study (clinicaltrials.gov identifier: NCT01160484) to evaluate whether a longer 4-week schedule using modified doses and schedules of IV dexamethasone (40 mg), bortezomib (1.0 mg/m(2)) and PLD (4.0 mg/m(2)) administered on days 1, 4, 8, and 11 with lenalidomide 10 mg daily on days 1-14 (DVD-R) would be effective and tolerated for patients with R/R MM. A total of 40 heavily pretreated patients were enrolled and 84.6% showed clinical benefit (complete response, 20.5%; very good partial response, 10.3%; partial response, 17.9%; minimal response, 35.9%) to the combination regimen. An additional 10.3% showed stable disease and 5.1% progressed while on study. The regimen was well tolerated, with a low incidence of adverse events such as fatigue (40%), thrombocytopenia (35%), neutropenia (35%), anemia (30%), peripheral neuropathy (25%) and pneumonia (15%). Thus, the DVD-R regimen is well tolerated and produces high response rates for patients with R/R MM.
Charged particle beam diagnostics is a key task in modern and future accelerator installations. The diagnostic tools are practically the “eyes” of the operators. The precision and resolution of the ...diagnostic equipment are crucial to define the performance of the accelerator. Transition and diffraction radiation (TR and DR) are widely used for electron beam parameter monitoring. However, the precision and resolution of those devices are determined by how well the production, transport and detection of these radiation types are understood. This paper reports on simulations of TR and DR spatial-spectral characteristics using the physical optics propagation (POP) mode of the Zemax advanced optics simulation software. A good consistency with theory is demonstrated. Also, realistic optical system alignment issues are discussed.
The Target Absorbers for Neutrals (TANs) are located in a high intensity radiation environment inside the tunnel of the Large Hadron Collider (LHC). TANs are positioned about 140 m downstream from ...the beam interaction points. Seven 40-cm long fused silica rods with different dopant specifications were irradiated in the TAN by the Beam RAte of Neutrals (BRAN) detector group duringp+pdata taking from 2016 to 2018 at the LHC. The peak dose delivered to the fused silica rods was 18 MGy. We report measurements of theNa22activation of the fused silica rods carried out at the University of Illinois at Urbana-Champaign and Argonne National Laboratory. At the end of the irradiation campaign, the maximumNa22activity observed wasA=21kBq/cm3corresponding to a density,ρ=2.5×1012/cm3, ofNa22 nuclei. fluka Monte Carlo simulations have been performed by the CERN fluka team to estimateNa22activities for the irradiated BRAN rod samples. The simulations reproduce theNa22activity profile measured along the rods, with a 35% underestimation of the experimental measurement results.
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