273 research outputs found
CW electron accelerator. Resonator cooling efficiency and thermal strain coupled analysis procedure
The procedure of the device under HF heating and turbulent liquid cooling displacement analysis by means of
existent program code is presented. The spatial computational cell size and other requirements ensuring the needed
computational accuracy are formulated. In order to illustrate the procedure developed an example analysis of the
Electron Resonance Accelerator of a mean beam power up to 300 kW cooling efficiency and deformation is provided.Представлена методика подготовки заданий по расчету в существующих программных комплексах деформации конструкций, подверженных нагреву токами высокой частоты и охлаждению турбулентным течением жидкости. Определены требования к размеру пространственной счётной ячейки и другие условия, обеспечивающие необходимую точность расчётов. Приведен расчет эффективности охлаждения и деформаций корпуса электронного ускорителя непрерывного действия со средней мощностью пучка до 300 кВт, основанный на связанном анализе протекающих процессов и иллюстрирующий применение представленной методики.Представлено методику підготовки завдань по розрахунку в діючих програмних комплексах деформації
конструкцій, що схильні до нагріву струмами високої частоти та охолодженню турбулентною течією рідини.
Визначені вимоги щодо розміру просторової розрахункової комірки та інші умови, що гарантують потрібну
точність розрахунку. Приведено розрахунок ефективності охолоджування та деформації корпусу
електронного прискорювача безперервної дії з середньою потужністю пучка до 300 кВт, оснований на
зв’язаному аналізу перебігу процесів та ілюструючий застосування представленої методики
A CW electron accelerator. The planned design and electrophysical characteristics
This paper presents a project on a CW high-power electron accelerator. The main part of the accelerator consists
of half-wave coaxial cavity resonator. The increment of electron energy is reached by repeated passing of an electron
beam via full diameter of the cavity in median plain dividing its bulk into halves. Successive redirection of the
electron beam into the cavity is performed by means of two rotary magnets. These magnets are placed outside the
cavity. Main parameters of the accelerator are as follows: electron beam energy 1.5…7.5 MeV, average beam power
above 300 kW, operating frequency 100 MHz.Представлен проект высокомощного ускорителя электронов непрерывного действия. Основной частью
ускорителя является полуволновой коаксиальный резонатор. Увеличение энергии электронов осуществляет-
ся при последовательном прохождении пучком полного диаметра коаксиального резонатора в делящей его
объем пополам поперечной медианной плоскости. Перенаправление движения электронного пучка в резона-
тор происходит при помощи двух поворотных магнитов, которые размещены вне резонатора. Основные па-
раметры ускорителя: энергия электронного пучка 1.5…7.5 МэВ, средняя мощность пучка 300 кВт, рабочая
частота 100 МГц.Представлено проект високопотужного прискорювача електронів безперервної дії. Основною частиною
прискорювача є півхвильовий коаксіальний резонатор. Збільшення енергії електронів здійснюється при
послідовному проходженні електронним пучком повного діаметра резонатора в середній площині, що
ділить його об’єм навпіл. Перенапрямок руху електронного пучка в резонатор відбувається за допомогою
двох поворотних магнітів, які розміщені поза резонатором. Основні параметри прискорювача: енергія
електронного пучка 1.5...7.5 МеВ, середня потужність пучка 300 кВт, робоча частота 100 МГц
Measurement of the branching fraction
The branching fraction is measured in a data sample
corresponding to 0.41 of integrated luminosity collected with the LHCb
detector at the LHC. This channel is sensitive to the penguin contributions
affecting the sin2 measurement from The
time-integrated branching fraction is measured to be . This is the most precise measurement to
date
Model-independent search for CP violation in D0→K−K+π−π+ and D0→π−π+π+π− decays
A search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states K−K+π−π+ and π−π+π+π− is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fb−1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the K−K+π−π+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the π−π+π+π− final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
Measurement of the mixing-induced CP-violating phase phi_s in Bs decays is of
prime importance in probing new physics. Here 7421 +/- 105 signal events from
the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp
collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A
time-dependent fit to the data yields a value of
phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard
Model expectation. No evidence of direct CP violation is found.Comment: 15 pages, 10 figures; minor revisions on May 23, 201
Search for the lepton-flavor-violating decays Bs0→e±μ∓ and B0→e±μ∓
A search for the lepton-flavor-violating decays Bs0→e±μ∓ and B0→e±μ∓ is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions at √s=7 TeV, collected by the LHCb experiment. The observed number of Bs0→e±μ∓ and B0→e±μ∓ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(Bs0→e±μ∓)101 TeV/c2 and MLQ(B0→e±μ∓)>126 TeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds
Absolute luminosity measurements with the LHCb detector at the LHC
Absolute luminosity measurements are of general interest for colliding-beam
experiments at storage rings. These measurements are necessary to determine the
absolute cross-sections of reaction processes and are valuable to quantify the
performance of the accelerator. Using data taken in 2010, LHCb has applied two
methods to determine the absolute scale of its luminosity measurements for
proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In
addition to the classic "van der Meer scan" method a novel technique has been
developed which makes use of direct imaging of the individual beams using
beam-gas and beam-beam interactions. This beam imaging method is made possible
by the high resolution of the LHCb vertex detector and the close proximity of
the detector to the beams, and allows beam parameters such as positions, angles
and widths to be determined. The results of the two methods have comparable
precision and are in good agreement. Combining the two methods, an overall
precision of 3.5% in the absolute luminosity determination is reached. The
techniques used to transport the absolute luminosity calibration to the full
2010 data-taking period are presented.Comment: 48 pages, 19 figures. Results unchanged, improved clarity of Table 6,
9 and 10 and corresponding explanation in the tex
Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) and the direct CP asymmetry in B0 -> K*0 gamma
The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma
and Bs0 phi gamma has been measured using an integrated luminosity of 1.0 fb-1
of pp collision data collected by the LHCb experiment at a centre-of-mass
energy of sqrt(s)=7 TeV. The value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 ->
phi gamma) = 1.23 +/- 0.06(stat.) +/- 0.04(syst.) +/- 0.10(fs/fd), where the
first uncertainty is statistical, the second is the experimental systematic
uncertainty and the third is associated with the ratio of fragmentation
fractions fs/fd. Using the world average value for BR(B0 -> K*0 gamma), the
branching fraction BR(Bs0 -> phi gamma) is measured to be (3.5 +/- 0.4) x
10^{-5}.
The direct CP asymmetry in B0 -> K*0 gamma decays has also been measured with
the same data and found to be A(CP)(B0 -> K*0 gamma) = (0.8 +/- 1.7(stat.) +/-
0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the
previous experimental results and theoretical expectations.Comment: 21 pages, 3 figues, 4 table
Absolute luminosity measurements with the LHCb detector at the LHC
Absolute luminosity measurements are of general interest for colliding-beam
experiments at storage rings. These measurements are necessary to determine the
absolute cross-sections of reaction processes and are valuable to quantify the
performance of the accelerator. Using data taken in 2010, LHCb has applied two
methods to determine the absolute scale of its luminosity measurements for
proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In
addition to the classic "van der Meer scan" method a novel technique has been
developed which makes use of direct imaging of the individual beams using
beam-gas and beam-beam interactions. This beam imaging method is made possible
by the high resolution of the LHCb vertex detector and the close proximity of
the detector to the beams, and allows beam parameters such as positions, angles
and widths to be determined. The results of the two methods have comparable
precision and are in good agreement. Combining the two methods, an overall
precision of 3.5% in the absolute luminosity determination is reached. The
techniques used to transport the absolute luminosity calibration to the full
2010 data-taking period are presented.Comment: 48 pages, 19 figures. Results unchanged, improved clarity of Table 6,
9 and 10 and corresponding explanation in the tex
Absolute luminosity measurements with the LHCb detector at the LHC
Absolute luminosity measurements are of general interest for colliding-beam
experiments at storage rings. These measurements are necessary to determine the
absolute cross-sections of reaction processes and are valuable to quantify the
performance of the accelerator. Using data taken in 2010, LHCb has applied two
methods to determine the absolute scale of its luminosity measurements for
proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In
addition to the classic "van der Meer scan" method a novel technique has been
developed which makes use of direct imaging of the individual beams using
beam-gas and beam-beam interactions. This beam imaging method is made possible
by the high resolution of the LHCb vertex detector and the close proximity of
the detector to the beams, and allows beam parameters such as positions, angles
and widths to be determined. The results of the two methods have comparable
precision and are in good agreement. Combining the two methods, an overall
precision of 3.5% in the absolute luminosity determination is reached. The
techniques used to transport the absolute luminosity calibration to the full
2010 data-taking period are presented.Comment: 48 pages, 19 figures. Results unchanged, improved clarity of Table 6,
9 and 10 and corresponding explanation in the tex
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