共查询到20条相似文献,搜索用时 15 毫秒
1.
E. Bagli L. Bandiera V. Guidi A. Mazzolari D. De Salvador A. Berra D. Lietti M. Prest E. Vallazza 《The European Physical Journal C - Particles and Fields》2014,74(1):1-7
I apply FDR—a recently introduced four-dimensional approach to quantum field theories (QFTs)—to the computation of the NLO QCD corrections to $H \rightarrow gg$ in the large top mass limit. The calculation involves all key ingredients of QCD—namely ultraviolet, infrared, and collinear divergences, besides $\alpha _S$ renormalization—and paves the way for successful use of FDR in massless one-loop QFT computations. I show in detail how the correct result emerges in FDR, and discuss the translation rules to dimensional regularization. 相似文献
2.
Ivanov YM Petrunin AA Skorobogatov VV Gavrikov YA Gelamkov AV Lapina LP Schetkovsky AI Vavilov SA Baranov VI Chesnokov YA Afonin AG Baranov VT Chepegin VN Guidi V Scandale W Vomiero A 《Physical review letters》2006,97(14):144801
Volume reflection predicted in the mid-1980s by Taratin and Vorobiev has been observed for the first time in the interactions of a 70 GeV proton beam with a short bent crystal. Incident protons deviate from convex atomic planes in the bulk of the crystal as a result of coherent interaction with bent lattice around the tangency point of particle trajectory with a curved atomic plane. The deflection angle 2theta(R) was found to be (39.5+/-2.0) microrad, or (1.65+/-0.08)theta(c) in terms of the critical angle for channeling. The process has a large probability with respect to channeling and takes place in the angular range equal to the bend angle of atomic planes. It could possibly open new fields of application of crystals in high-energy particle beam optics. 相似文献
3.
4.
Yu. M. Ivanov N. F. Bondar’ Yu. A. Gavrikov A. S. Denisov A. V. Zhelamkov V. G. Ivochkin S. V. Kos’yanenko L. P. Lapina A. A. Petrunin V. V. Skorobogatov V. M. Suvorov A. I. Shchetkovsky A. M. Taratin W. Scandale 《JETP Letters》2006,84(7):372-376
The volume reflection of 1-GeV protons by a bent crystal has been observed. The crystal is made of single crystal silicon.
The (111) atomic planes are bent owing to the elastic quasimosaicity effect, which makes it possible to reduce the crystal
length for a beam to 30 μm. It is found that the probability of the reflection effect is higher than the probability of the
channeling effect (0.71 vs. 0.63), and the deflection angle of the protons reflected inside the crystal is equal to 1.39 ±
0.04 in terms of the critical angle for channeling under the conditions of the experiment (170 μrad). The width of the reflected
peak is equal to 1.76 ± 0.04 in the same units. The protons that are not involved in channeling at the angular position of
maximum channeling undergo volume reflection and are deflected in the direction opposite to the channeled beam by the angle
1.01 ± 0.05 in terms of the critical angle for channeling. The width of the reflected peak is equal to 1.94 ± 0.08 in the
same units.
Original Russian Text ? Yu.M. Ivanov, N.F. Bondar’, Yu.A. Gavrikov, A.S. Denisov, A.V. Zhelamkov, V.G. Ivochkin, S.V. Kos’yanenko,
L.P. Lapina, A.A. Petrunin, V.V. Skorobogatov, V.M. Suvorov, A.I. Shchetkovsky, A.M. Taratin, W. Scandale, 2006, published
in Pis’ma v Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2006, Vol. 84, No. 7, pp. 445–450. 相似文献
5.
W. Scandale A. Vomiero E. Bagli S. Baricordi P. Dalpiaz M. Fiorini V. Guidi A. Mazzolari D. Vincenzi R. Milan Gianantonio Della Mea E. Vallazza A.G. Afonin Yu.A. Chesnokov V.A. Maisheev I.A. Yazynin V.M. Golovatyuk A.D. Kovalenko A.M. Taratin A.S. Denisov Yu.A. Gavrikov Yu.M. Ivanov L.P. Lapina L.G. Malyarenko V.V. Skorobogatov V.M. Suvorov S.A. Vavilov D. Bolognini S. Hasan A. Mattera M. Prest V.V. Tikhomirov 《Physics letters. [Part B]》2009
Multiple volume reflection by different planes in a bent silicon crystal with its 〈111〉 axis orientation close to the beam direction was observed for the first time for 400 GeV/c protons at the CERN SPS. The proton beam was deflected to the side opposite to the crystal bend by an angle of about 67 μrad, which is five times larger than in a single volume reflection by the (110) bent planes. The registered efficiency of one side deflection was about 84%. It was shown that multiple volume reflection transforms to a single volume reflection when the orientation angle of the 〈111〉 axis relative to the beam direction is increased. 相似文献
6.
G. V. Kovalev 《JETP Letters》2008,87(2):87-91
The scattering of fast charged particles in a bent crystal has been analyzed in the framework of relativistic classical mechanics. The expressions obtained for the deflection function are in satisfactory agreement with the experimental data for the volume reflection of relativistic protons obtained by Yu. M. Ivanov et al., Phys. Rev. Lett. 97, 144801 (2006); Yu. M. Ivanov et al., Pis’ma Zh. Eksp. Teor. Fiz. 84, 445 (2006) [JETP Lett. 84, 372 (2006)]; and W. Scandale et al., Phys. Rev. Lett. 98, 154801 (2007). The features of the scattering of the particles on ring potentials are considered in a wide range of impact parameters. 相似文献
7.
A. G. Afonin V. T. Baranov G. I. Britvich A. P. Bugorskii V. I. Kotov A. E. Kushnirenko V. A. Maisheev V. A. Pikalov V. N. Chepegin Yu. A. Chesnokov I. A. Yazynin Yu. M. Ivanov V. V. Skorobogatov 《JETP Letters》2008,88(7):414-417
The emission of photons in the motion of a 10-GeV positron beam in bent silicon crystals has been experimentally investigated. The experimental data are compared with the theoretical calculations. 相似文献
8.
《Physics letters. A》1996,223(3):186-188
The excitation of one-dimensional nonlinear relativistic wake-waves in an electron-positron plasma by an ultrarelativistic proton beam is discussed on the basis of a self-consistent analytical model. It is shown that in contrast to a common plasma with heavy ions these waves are have an oscillation character at any ratio of the beam density and that of the electron-positron plasma. 相似文献
9.
We present an efficient photorefractive volume hologram recording technique with a pulsed signal beam and continuous reference-beam illumination. The grating envelope can be simply controlled by manipulation of the duty cycle of the signal beam. Thus, for any grating coupling strength and different initial reference-signal intensity ratios, the diffraction efficiency can be maximized with this technique and can be greatly increased in comparison with that of the conventional recording technique. 相似文献
10.
Scandale W Vomiero A Baricordi S Dalpiaz P Fiorini M Guidi V Mazzolari A Della Mea G Milan R Ambrosi G Bertucci B Burger WJ Zuccon P Cavoto G Luci C Santacesaria R Valente P Vallazza E Afonin AG Chesnokov YA Maisheev VA Yazynin IA Kovalenko AD Taratin AM Denisov AS Gavrikov YA Ivanov YM Lapina LP Malyarenko LG Skorobogatov VV Suvorov VM Vavilov SA Bolognini D Hasan S Mozzanica A Prest M 《Physical review letters》2008,101(16):164801
Beam deflection due to axial channeling in a silicon crystal bent along the 111 axis was observed with 400 GeV/c protons at the CERN Super Proton Synchrotron. The condition for doughnut scattering of protons by the atomic strings of the crystal was attained. Such a condition allowed one to observe a beam deflection of 50 murad with about 30% efficiency. The contribution of hyperchanneled states of protons to the observed beam deflection was less than 2% according to simulation results. 相似文献
11.
The features of the intensity distribution over the exit surface of a uniformly bent crystal have been investigated in reflection
geometry. Experiments have been performed using thin-layer heterostructures Si(1−x)Ge
x
/Si. For heterosystems, internal stresses induced in the film and substrate lead to an elastic bending of the whole system.
The section topographs exhibit deformation interference fringes. It is important that the contrast of this interference pattern
is almost one order of magnitude higher than the contrast in the case of Bragg scattering in a perfect crystal. The observed
interference pattern depends on the radius of bending of the crystal. As the bending radius increases, all maxima shift toward
the basic Bragg peak. Correspondingly, all distances between the interference fringes decrease. It has been shown that the
positions of intensity maxima do not depend on the sign of the crystal bending. For a negative sign of the radius of the crystal
bending (positive strain gradient), the integrated intensity increases. The results of the numerical simulation of the diffraction
images agree well with the experimental topographs. A comparison of the numerical simulation of the interference pattern with
the experimental topographs makes it possible to exactly determine the radius of the crystal bending (4%). The formulas describing
the positions of interference maxima as a function of the bending radius of the sample have been obtained using the results
of the numerical simulation of the experiment. 相似文献
12.
Afonin AG Baranov VT Biryukov VM Breese MB Chepegin VN Chesnokov YA Guidi V Ivanov YM Kotov VI Martinelli G Scandale W Stefancich M Terekhov VI Trbojevic D Troyanov EF Vincenzi D 《Physical review letters》2001,87(9):094802
A silicon crystal was used to channel and extract 70 GeV protons from the U-70 accelerator with an efficiency of 85.3+/-2.8%, as measured for a beam of approximately 10(12) protons directed towards crystals of approximately 2 mm length in spills of approximately 2 s duration. The experimental data follow very well the prediction of Monte Carlo simulations. This demonstration is important in devising a more efficient use of the U-70 accelerator in Protvino and provides crucial support for implementing crystal-assisted slow extraction and collimation in other machines, such as the Tevatron, RHIC, the AGS, the SNS, COSY, and the LHC. 相似文献
13.
W. Scandale A. Vomiero E. Bagli S. Baricordi P. Dalpiaz M. Fiorini V. Guidi A. Mazzolari D. Vincenzi R. Milan Gianantonio Della Mea E. Vallazza A.G. Afonin Yu.A. Chesnokov V.A. Maisheev I.A. Yazynin V.M. Golovatyuk A.D. Kovalenko A.M. Taratin A.S. Denisov Yu.A. Gavrikov Yu.M. Ivanov L.P. Lapina L.G. Malyarenko V.V. Skorobogatov V.M. Suvorov S.A. Vavilov D. Bolognini S. Hasan M. Prest 《Physics letters. [Part B]》2010
Different kinds of deflection in a silicon crystal bent along the 〈111〉 axis was observed for 150 GeV/c negative particles, mainly π− mesons, at one of the secondary beams of the CERN SPS. The whole beam was deflected to one side in quasi-bound states of doughnut scattering (DSB) by atomic strings with the efficiency (95.4 ± 0.2)% and with the peak position close to the bend crystal angle, α=185 μrad. It was observed volume capture of π− mesons into the DSB states with a probability higher than 7%. A beam deflection opposite to the crystal bend was observed for some orientations of the crystal axis due to doughnut scattering and subsequent multiple volume reflections of π− mesons by different bent planes crossing the axis. 相似文献
14.
15.
A. A. Arkhipenko A. G. Afonin V. T. Baranov G. I. Britvich V. I. Kotov V. A. Maisheev A. V. Maksimov S. F. Reshetnikov V. N. Chepegin Yu. A. Chesnokov I. A. Yazynin 《JETP Letters》2008,88(4):229-231
The measurements of the efficiency of the extraction of protons from the U-70 accelerator with the use of silicon crystals with bending angles of 36 and 64 mrad are reported. The data are confirmed by computer simulation. Proposals are made on the use of several crystals for the extraction of particles from the U-70 accelerator in the carbon ion acceleration mode. 相似文献
16.
It has been shown that the use of a bent crystal with a variable curvature radius makes it possible to reduce the fraction
of dechanneled particles by an order of magnitude. This effect enables the strong reduction of the particle density at the
edge of a collimator or the partition of a septum upon the multi-turn extraction of a beam from a ring accelerator. In particular,
the beam extraction efficiency at the U-70 synchrotron and Large Hadron Collider can be increased to 95 and 99.65%, respectively. 相似文献
17.
The layered growth and doping of silicon crystal is investigated on the basis of the kinetic theory of crystal growth. The density of atomic sticking sites on a (110) oriented Si surface is determined. The nonlinear dependences of the doping impurity concentration in the growing crystal on its concentration in the source (the density of the impurity atomic beam), the crystal growth rate, and the growth temperature are derived. The theoretical doping characteristics of silicon with phosphor are found to be in good agreement with the experimental data.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 24–28, January, 1982. 相似文献
18.
Y. H. Ja 《Optical and Quantum Electronics》1989,21(2):151-154
We propose a scheme for optical beam deflection using dynamic volume reflection gratings. Since the direction change of the diffracted beam with the recording wavelength is much larger for a reflection grating a passive beam-tilting element may not be required. 相似文献
19.
W. Scandale A. Vomiero E. Bagli S. Baricordi P. Dalpiaz M. Fiorini V. Guidi A. Mazzolari D. Vincenzi R. Milan Gianantonio Della Mea E. Vallazza A.G. Afonin Yu.A. Chesnokov V.A. Maisheev I.A. Yazynin V.M. Golovatyuk A.D. Kovalenko A.M. Taratin A.S. Denisov Yu.A. Gavrikov Yu.M. Ivanov L.P. Lapina L.G. Malyarenko V.V. Skorobogatov V.M. Suvorov S.A. Vavilov D. Bolognini S. Hasan A. Mattera M. Prest S. Shiraishi 《Physics letters. [Part B]》2009,681(3):233-236
Deflection due to planar channeling and volume reflection in short bent silicon crystals was observed for the first time for 150 GeV/c negative particles, π− mesons, at one of the secondary beams of the CERN SPS. The deflection efficiency was about 30% for channeling and higher than 80% for volume reflection. Volume reflection occurs, in spite of the attractive character of the forces acting between the particles and the crystal planes, in a wide angular range of the crystal orientations determined by the crystal bend angle. 相似文献
20.
利用透射波函数和由菲涅尔公式求解反射相位差并对其求导的方法,分析了非常偏振光在单轴晶体表面发生的全反射现象,求解出晶体光轴在入射面内时,非常偏振光从各向同性介质入射到晶体和从晶体出射到各向同性介质两种情况的隐失波穿透深度和Goos-Hnchen位移的一般表达式。通过计算机模拟给出了单轴晶体为方解石和水晶情况时的穿透深度和Goos-Hnchen位移图像。结果表明,对于不同的晶体,光轴的取向对穿透深度和Goos-Hnchen位移的影响是明显不同的,若选取合适的晶体、光轴取向和入射角,可以得到较大的隐失波穿透深度和Goos-Hnchen位移。 相似文献