EUV spectra of highly-charged ions W54+^{54+}-W63+^{63+} relevant to ITER diagnostics

We report the first measurements and detailed analysis of extreme ultraviolet (EUV) spectra (4 nm to 20 nm) of highly-charged tungsten ions W$^{54+}$ to W$^{63+}$ obtained with an electron beam ion trap (EBIT). Collisional-radiative modelling is used to identify strong electric-dipole and magnetic-dipole transitions in all ionization stages. These lines can be used for impurity transport studies and temperature diagnostics in fusion reactors, such as ITER. Identifications of prominent lines from several W ions were confirmed by measurement of isoelectronic EUV spectra of Hf, Ta, and Au. We also discuss the importance of charge exchange recombination for correct description of ionization balance in the EBIT plasma.Comment: 11 pages, 4 figure

Моделирование пробегов и потерь энергии высокоэнергетических ионов в однослойных и многослойных материалах

Linear and mass ranges of protons and argon ions in aluminum, alumina, bismuth, and W77.7Cu22.3 composite shields were calculated using the SRIM software package. It is shown that the protection efficiency against high-energy ions by materials with large atomic charge (Z) values is higher, from the position of linear ranges of particles, and lower, from the position of mass ranges, in comparison with materials with low Z values. The dependence of the threshold energy on the serial number of particles for aluminum, bismuth, and composite W77.7Cu22.3 shields is determined. The ionization loss spectra for the passage of both protons with an energy of 20 MeV and krypton ions with an energy of 7.75 GeV through multilayer Bi/Al/Al2O3 and Al/Al2O3/Bi structures were calculated. These results showed that the braking of high-energy particles in the case when the first layer contains a heavy element is higher than in the case when the first layer contains a light element. The influence of the sequence in the arrangement and thickness of the layers in the multilayer structures of the Bi/Al/Al2O3 system on the efficiency of protection against high-energy ions was studied. It is shown that the nature of the dependences R(E) and ion energy losses are determined by the sequence of arrangement of individual layers, which is due to the difference in the conversion of the spectra by the material of the first layer. The studied radiation shields can be used in aerospace and nuclear technologies, as well as in many scientific and medical devices, and can be used to protect against the effects of a wide range of ionizing radiation (electrons, protons, heavy charged particles, etc.).С помощью программного комплекса SRIM рассчитаны линейные и массовые пробеги протонов и ионов аргона в экранах из алюминия, оксида алюминия, висмута и композита W77,7Cu22,3. Показано, что эффективность защиты от высокоэнергетических ионов материалами с большими значениями заряда ядер атомов (Z) выше с позиции линейных пробегов частиц и ниже с позиции массовых пробегов, чем материалами с низкими значениями Z. Определена зависимость пороговой энергии от Z высокоэнергетических ионов для экранов из алюминия, висмута и композита W77,7Cu22,3. Проведены расчеты спектров потерь на ионизацию при прохождении протонов с энергией 20 МэВ и ионов криптона с энергией 7,75 ГэВ через многослойные структуры Bi/Al/Al2O3 и Al/Al2O3/Bi. Расчеты показали, что торможение высокоэнергетических частиц в случае, когда первый слой содержит тяжелый элемент, выше, чем в случае, когда первый слой содержит легкий элемент. Изучено влияние последовательности в расположении и толщины слоев в многослойных структурах системы Bi/Al/Al2O3 на эффективность защиты от высокоэнергетических ионов. Показано, что характер зависимостей R(E) и потерь энергии ионов определяется очередностью расположения отдельных слоев, что связано с различием преобразования спектров материалом первого слоя. Рассмотренные экраны радиационной защиты могут быть использованы в элементах и аппаратуре ракетно-космической техники, могут обеспечить требования по устойчивости к воздействию различных видов ионизирующих излучений (электронное, протонное, гамма-излучение, тяжелые заряженные частицы и др.)

Design, performance, and calibration of CMS forward calorimeter wedges

We report on the test beam results and calibration methods using high energy electrons, pions and muons with the CMS forward calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (3 <= vertical bar eta vertical bar <= 5), and is essential for a large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels in Higgs production. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h approximate to 5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as a/root E circle plus b. The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Design, Performance and Calibration of the CMS Forward Calorimeter Wedges

We report on the test beam results and calibration methods using charged particles of the CMS Forward Calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (3\l |\eta| \le 5), and is essential for large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h \approx 5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as a/\sqrt{E} + b. The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%

Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

Peer reviewe

Design, Performance, and Calibration of CMS Hadron-Barrel Calorimeter Wedges

Extensive measurements have been made with pions, electrons and muons on four production wedges of the Compact Muon Solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. Data were taken both with and without a prototype electromagnetic lead tungstate crystal calorimeter (EB) in front of the hadron calorimeter. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. These measurements set the absolute calibration of the HB prior to first pp collisions to approximately 4%