In the scope of the Physics Beyond Colliders studies, the gamma-factory initiative proposes the use of partially stripped ions as a driver of a new type of high-intensity photon source in CERN Large ...Hadron Collider (LHC). In 2018, the LHC accelerated and stored partially strippedPb20881+ions for the first time. The collimation system efficiency recorded during this test was found to be prohibitively low, so that only a very low-intensity beam could be stored without the risk of triggering a beam dump when regular, minor beam losses occur. The worst losses were localized in the dispersion suppressor of the betatron-cleaning insertion. This article presents an analysis to understand in detail the source of these losses. Based on this understanding, possible mitigation measures that could significantly improve the cleaning efficiency and enable regular operation with partially stripped ions in the future are developed.
Micrometer-sized dust particles present in the Large Hadron Collider (LHC) beam pipe are believed to have caused many thousands of sporadic beam loss events around the LHC. These so-called ...unidentified falling objects (UFOs) have been under continuous study since the start of high intensity beam operation in the LHC due to their impact on the LHC availability: 139 beam dumps and 12 magnet quenches during Run II (2015–2018) alone. To mitigate the impact of UFOs on future accelerators such as the High Luminosity LHC and the Future Circular Collider, it is fundamental to foster a better understanding of these beam loss events. In this paper, key observations made since the start of LHC operation are summarized and the prevailing UFO hypothesis is confronted by a compilation of observations acquired during Run II. In particular, it is shown that UFOs must carry an initial negative charge before entering the proton beam, or that they are by some other means accelerated toward the beam not only by gravity. A simulation model for the dynamics of the dust particles and their interaction with the beam was developed over the years. This model is improved and validated by measurements. It is however also shown that a subset of observed beam losses, which contain a positive time profile skewness, cannot be explained by it.
Halo diffusion measurements at the CERN Large Hadron Collider (LHC) were conducted with beams for physics at 6.5 TeV by means of collimator scans, carried out between 2016 and 2018. From the time ...evolution of the beam losses recorded during a collimator scan, in which collimator jaws are moved in steps toward the beam core cutting beam tails, one can extract information on the halo diffusion and its population as a function of the transverse amplitude. In this paper, results of the first scans performed at different beam intensities for both planes and both beams using the primary collimators of the betatron-cleaning system are presented. The scans were performed with squeezed optics and colliding beams after a few hours of regular physics production, during so-called end-of-fill measurements. Beam losses are measured with ionization chambers close to the collimators, which enable 1 and 100 Hz acquisitions, as well as diamond beam loss monitors, which enable turn-by-turn and bunch-by-bunch acquisitions. Parametric fits of a diffusion model are applied to the time profile of losses, for both total and individual bunch intensity. The analysis of the measurements performed in various conditions was used to estimate the diffusion coefficient as a function of the transverse amplitude and the population of LHC beam tails.
Micrometer sized particles entering the LHC beam (the so called Unidentified Falling Objects or UFOs) are a known cause of localized beam losses since the beginning of high intensity beam operation, ...however the origin of these particles is not fully known. Their effect limits LHC availability by causing premature dumps due to excessive beam losses and occasionally even magnet quenches. This could become an important limitation for future accelerators such as the High Luminosity upgrade of the LHC (HL-LHC) and the Future Circular Collider (FCC). The dynamics of these UFOs was investigated in two dedicated experiments. In the first experiment, it was shown that the transverse movements of these particles can be studied by observing bunch-by-bunch losses from bunches with different horizontal and vertical emittances. In the second experiment, UFO-like events around the 16L2 interconnect in the LHC, which has seen intense UFO activity in 2017, were studied with the above method. This paper summarizes the results of both experiments.
We discuss the possibility of creating novel research tools by producing and storing highly relativistic beams of highly ionised atoms in the CERN accelerator complex, and by exciting their atomic ...degrees of freedom with lasers to produce high-energy photon beams. Intensity of such photon beams would be by several orders of magnitude higher than offered by the presently operating light sources, in the particularly interesting gamma-ray energy domain of 0.1-400 MeV. In this energy range, the high-intensity photon beams can be used to produce secondary beams of polarised electrons, polarised positrons, polarised muons, neutrinos, neutrons and radioactive ions. New research opportunities in a wide domain of fundamental and applied physics can be opened by the Gamma Factory scientific programme based on the above primary and secondary beams.
Water Rescue in Poland Gorzawski, Jarosław
Zeszyty Naukowe Wyższej Szkoły Finansów i Prawa w Bielsku-Białej,
4/2019, Letnik:
23, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Voluntary Water Rescue Service (commonly referred to as WOPR) operates pursuant to the Polish act of 18 August 2011 concerning the safety of persons present in water areas. The main tasks of the ...service include: undertaking rescue operations, organizing and providing aid to persons involved in accidents (that means sudden events that occur during swimming, bathing or practicing sports or recreational activities in water areas, which could result in an injury of an organ of the body or in health impairment) or to persons exposed to a threat of losing their life or health while in or near water.
Size, morphology and microstructure of Palas soot, Diesel soot and of Diesel soot/ammonium sulfate mixtures were studied by transmission electron microscopy (TEM). The diameter of the primary ...particles derived from TEM is
6.6±1.7
nm
for Palas soot and
22.6±6.0
nm
for Diesel soot. Palas soot predominantly consists of amorphous carbon. In a few cases, nanocrystalline graphite with domain sizes on the order of 1 nm were observed. Primary particles of Diesel soot always show an onion-shell structure of nanocrystalline graphite with domain sizes between 2–
3
nm
. Fractal properties of 37 Diesel soot agglomerates were determined from TEM images by two different techniques. The average fractal dimension of Diesel soot derived from TEM is 1.70±0.13. TEM further showed that the initially external mixture of Diesel soot and ammonium sulfate developed with time in a significant degree of internal mixing.
A second independent approach to determine the fractal properties of soot is based on computer simulations of the aerosol dynamics. A good reproduction of the time evolution of mass and number concentrations and of the mobility size distribution was achieved. The primary particle diameters obtained from the computer simulations (
7.3±0.8
nm
for Palas soot,
25±3
nm
for Diesel soot) are in excellent agreement with the TEM results. The fractal dimension of Diesel soot received from the COSIMA algorithm of 1.9±0.2 (overlap of primary particles was taken into consideration) is consistent with the value obtained from TEM image analysis. For Palas soot, the computer simulation yielded a fractal dimension of 2.0±0.1 (overlap was not corrected, as the overlap coefficient is not known).
Water Rescue in Poland Jarosław Gorzawski
Zeszyty Naukowe Wyższej Szkoły Finansów i Prawa w Bielsku-Białej,
02/2016, Letnik:
23, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Voluntary Water Rescue Service (commonly referred to as WOPR) operates pursuant to the Polish act of 18 August 2011 concerning the safety of persons present in water areas. The main tasks of the ...service include: undertaking rescue operations, organizing and providing aid to persons involved in accidents (that means sudden events that occur during swimming, bathing or practicing sports or recreational activities in water areas, which could result in an injury of an organ of the body or in health impairment) or to persons exposed to a threat of losing their life or health while in or near water.
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