作者机构：
[Huang, Guangming; Deng, Wenjing; Zhou, Wei; Sun, Xiangming; Gao, Chaosong; Guo, Di] Cent China Normal Univ, PLAC, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China
通讯机构：
[Huang, Guangming] C;Cent China Normal Univ, PLAC, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.
关键词：
time interval measurement;time-to-digital converter (TDC);coarse-fine architecture;analog-digital hybrid interpolation;calibration
摘要：
An innovative high-precision coarse-fine time-to-digital converter (TDC) is presented. The TDC architecture mainly consists of a coarse counter and a delay-line-based analog-digital hybrid interpolator. In order to improve the precision, the key timing control of the interpolator is provided by a novel customized synchronizer. Comparing to the traditional delay-line-based interpolator, the proposed analog-digital hybrid interpolator using the multi-voltage sampling technique improves the resolution significantly. A prototype chip has been fabricated in a 0.35 mu m CMOS process. After the calibration and calculation based on fitting algorithms, the TDC prototype reaches a dynamic range of 512 ns and a single-channel single-shot precision of 6 ps using the external look-up table (LUT) for the interpolator.
期刊：
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT,2019年924:82-86 ISSN：0168-9002
通讯作者：
Zhang, Ying
作者机构：
[Huang, Guangming; Xiao, Le; Zhang, Li; Li, Yashu; Zhou, Wei; Yang, Ping; Ren, Weiping; Sun, Xiangming; Liu, Jianchao; You, Bihui; Gao, Chaosong; Liu, Jun; Huang, Xing] Cent China Normal Univ, PLAC, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;[Zhang, Ying] State Key Lab Particle Detect & Elect, Beijing 100049, Peoples R China.;[Zhang, Ying] Inst High Energy Phys, 19B YuquanLu, Beijing 100049, Peoples R China.
通讯机构：
[Zhang, Ying] I;Inst High Energy Phys, 19B YuquanLu, Beijing 100049, Peoples R China.
会议名称：
11th International Hiroshima Symposium on the Development and Application of Semiconductor Tracking Detectors (HSTD) in conjunction with 2nd Workshop on SOI Pixel Detector (SOIPIX)
会议时间：
DEC 11-15, 2017
会议地点：
Okinawa Inst sci & Technol Grad Univ, Okinawa, JAPAN
会议主办单位：
Okinawa Inst sci & Technol Grad Univ
关键词：
Monolithic Active Pixel Sensor (MAPS);In-matrix zero-suppression;Vertex detector;CEPC
摘要：
The Circular Electron Positron Collider (CEPC) is proposed as a Higgs factory for precision measurement of properties of the Higgs boson. The CEPC vertex detector requires low material budget, high spatial resolution, fast readout and low power consumption. Monolithic Active Pixel Sensor (MAPS), as one of the promising candidate technologies, has been studied within the R&D activities for the CEPC vertex detector. This proceeding introduces recent development of a MAPS prototype using the TowerJazz 180 nm CMOS Image Sensor process. Two different binary front-end circuits have been designed to explore an in-pixel front-end structure suitable for a compact pixel in combination with an in-matrix sparsified readout circuitry. To achieve high granularity together with fast readout speed, a new architecture of asynchronous data-driven matrix readout has been implemented. The prototype contains 128 rows and 64 columns featuring a small pixel pitch of 25 mu m. The address of one hit pixel can be read out in 25 ns. This work presents the design of the prototype, which is currently under test.
摘要：
In this paper, we study how pixel size influences energy resolution for a proposed pixelated detector—a high sensitivity, low cost, and real-time radon monitor based on a Topmetal-
$${II}^-$$
time projection chamber (TPC). This monitor was designed to improve spatial resolution for detecting radon alpha particles using Topmetal-
$${II}^-$$
sensors assembled by a 0.35 μm CMOS integrated circuit process. Owing to concerns that small pixel size might have the side effect of worsening energy resolution due to lower signal-to-noise ratio, a Geant4-based simulation was used to investigate the dependence of energy resolution on pixel sizes ranging from 60 to 600 μm. A non-monotonic trend in this region shows the combined effect of pixel size and threshold on pixels, analyzed by introducing an empirical expression. Pixel noise contributes 50 keV full-width at half-maximum energy resolution for 400 μm pixel size at 1–4
$$\sigma$$
threshold that is comparable to the energy resolution caused by energy fluctuations in the TPC ionization process (
$$\sim \,20$$
keV). The total energy resolution after combining both factors is estimated to be 54 keV for a pixel size of 400 μm at 1–4
$$\sigma$$
threshold. The analysis presented in this paper would help choosing suitable pixel size for future pixelated detectors.
通讯机构：
[Fan, Yan] C;Cent China Normal Univ, PLAC, Key Lab Quark & Lepton Phys, MOE,Dept Phys Sci & Technol, Wuhan 430079, Hubei, Peoples R China.
关键词：
Bragg peak;Carbon ion;Prompt c-ray;Geant4
摘要：
Real-time monitoring of the Bragg peak location of carbon ions is urgently required for the quality control of hadron therapy. In this study, we design an annular detector to monitor the Bragg peak location of carbon ions with Geant4 simulation. This 360° surrounding structure has a high detection efficiency for the small-dose situation. The detector consists of a multilayered collimator system and an NaI scintillator for prompt gamma counting. The multilayered collimator includes a lead layer to prevent unwanted gammas and the paraffin and boron carbide layers to moderate and capture fast neutrons. An inclination of the detector further diminishes the background signal caused by neutrons. The detector, with optimized parameters, is applicable to carbon ions of different energies. In addition, the scintillator is replaced by an improved EJ301 organic liquid scintillator to discriminate gammas and neutrons. Inserting thin Fe slices into the liquid scintillator improves the energy deposition efficiency. The Bragg peak location of 200 MeV/u carbon ions can be monitored by prompt gamma detection with the improved liquid scintillator.
通讯机构：
[Han, K; Ji, XD] S;[Ji, XiangDong] U;Shanghai Jiao Tong Univ, Shanghai Lab Particle Phys & Cosmol, INPAC, Shanghai 200240, Peoples R China.;Shanghai Jiao Tong Univ, Shanghai Lab Particle Phys & Cosmol, Dept Phys & Astron, Shanghai 200240, Peoples R China.;Univ Maryland, Dept Phys, College Pk, MD 20742 USA.
关键词：
neutrinoless double beta decay;lepton number vlolation;underground experiment;TPC;Micromegas
摘要：
Searching for the neutrinoless double beta decay (NLDBD) is now regarded as the topmost promising technique to explore the nature of neutrinos after the discovery of neutrino masses in oscillation experiments. PandaX-III (particle and astrophysical xenon experiment III) will search for the NLDBD of ~(136)Xe at the China Jin Ping Underground Laboratory (CJPL). In the first phase of the experiment, a high pressure gas Time Projection Chamber (TPC) will contain 200 kg, 90% ~(136)Xe enriched gas operated at 10 bar. Fine pitch micro-pattern gas detector (Microbulk Micromegas) will be used at both ends of the TPC for the charge readout with a cathode in the middle. Charge signals can be used to reconstruct the electron tracks of the NLDBD events and provide good energy and spatial resolution. The detector will be immersed in a large water tank to ensure ～5 m of water shielding in all directions. The second phase, a ton-scale experiment, will consist of five TPCs in the same water tank, with improved energy resolution and better control over backgrounds.
通讯机构：
[Yang, Ping] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys, PLAC, MOE, Wuhan 430079, Hubei, Peoples R China.
关键词：
CEPC vertex detector;CPS;asynchronous;data-driven readout;low power
摘要：
The Circular Electron Positron Collider (CEPC) is proposed as a Higgs boson and/or Z boson factory for high-precision measurements on the Higgs boson. The precision of secondary vertex impact parameter plays an important role in such measurements which typically rely on flavor-tagging. Thus silicon CMOS Pixel Sensors (CPS) are the most promising technology candidate for a CEPC vertex detector, which can most likely feature a high position resolution, a low power consumption and a fast readout simultaneously. For the R&D of the CEPC vertex detector, we have developed a prototype MIC4 in the Towerjazz 180 nm CMOS Image Sensor (CIS) process. We have proposed and implemented a new architecture of asynchronous zero-suppression data-driven readout inside the matrix combined with a binary front-end inside the pixel. The matrix contains 128 rows and 64 columns with a small pixel pitch of 25 μm. The readout architecture has implemented the traditional OR-gate chain inside a super pixel combined with a priority arbiter tree between the super pixels, only reading out relevant pixels. The MIC4 architecture will be introduced in more detail in this paper. It will be taped out in May and will be characterized when the chip comes back.
通讯机构：
[Huang, Guangming] C;[Gong, Datao] S;Cent China Normal Univ, Dept Phys, Wuhan 430079, Hubei, Peoples R China.;Southern Methodist Univ, Dept Phys, Dallas, TX 75275 USA.
会议名称：
10th International Hiroshima Symposium on the Development and Application of Semiconductor Tracking Detectors (HSTD)
会议时间：
SEP 25-29, 2015
会议地点：
Xian Jiaotong Univ, Xian, PEOPLES R CHINA
会议主办单位：
Xian Jiaotong Univ
关键词：
Front-end electronics for detector readout;Digital electronic circuits;Trigger concepts and systems (hardware and software)
摘要：
In this paper, we present the design and test results of an encoder integrated circuit for the ATLAS Liquid Argon Calorimeter trigger upgrade. The encoder implements a low-latency and low -overhead line code called LOCic. The encoder operates at 320 MHz with a latency of no greater than 21 ns. The overhead of the encoder is 14.3%. The encoder is an important block of the transmitter ASIC LOCx2, which is prototyped with a commercial 0.25 pm Silicon-on-Sapphire CMOS technology and packaged in a 100 -pin QFN package. (C) 2016 Published by Elsevier B.V.
通讯机构：
[Sun, Xiangming] C;Cent China Normal Univ, PLAC, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.
关键词：
Topmetal;Pixel;Low noise sensor;Cryogenic temperature
摘要：
Topmetal-II- is a highly pixelated direct charge sensor that contains a 72 x 72 pixel array of 83.tm pitch size. The key feature of Topmetal-II- is that it can directly collect charges via metal nodes of each pixel to form two-dimensional images of charge cloud distributions. Topmetal-II- was proved to measure charged particles without amplification at room temperature. To measure its performance at cryogenic temperature, a Topmetal-II- sensor is embedded into a liquid nitrogen dewar. The results presented in this paper show that Topmetal-II- can also operate well at this low temperature with a noise (ENC) of 12 e(-) lower than that at room temperature (13 e(-)). From the noise perspective, Topmetal-II- is a promising candidate for the next generation readout of liquid argon and xenon time projection chamber (TPC) used in experiments searching for neutrinoless double beta decay and dark matter. (C) 2016 Elsevier B.V. All rights reserved.
作者：
Agakishiev, H.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A. V.;Alekseev, I.;...
期刊：
PHYSICAL REVIEW C,2014年89(4) ISSN：2469-9985
通讯作者：
Agakishiev, H.
作者机构：
[Kechechyan, A.; Kizka, V.; Agakishiev, H.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Heppelmann, S.; Vokal, S.] Joint Inst Nucl Res, Dubna 141980, Russia.;[Underwood, D. G.; Krueger, K.; Bridgeman, A.; Spinka, H. M.] Argonne Natl Lab, Argonne, IL 60439 USA.;[Ullrich, T.; Pile, P.; Lamont, M. A. C.; LeVine, M. J.; Ljubicic, T.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Videbaek, F.; Fine, V.; Fisyak, Y.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Christie, W.; Arkhipkin, D.; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Gordon, A.; Landgraf, J. M.; Love, W. A.; Yip, K.; Didenko, L.; Guryn, W.; Van Buren, G.; Lee, J. H.] Brookhaven Natl Lab, Upton, NY 11973 USA.;[Perkins, C.; Crawford, H. J.; Engelage, J.; Alford, J.; Judd, E. G.] Univ Calif Berkeley, Berkeley, CA 94720 USA.;[Draper, J. E.; Cebra, D.; Brovko, S. G.; Beavis, D. R.; Sangaline, E.; Reed, R.; de la Barca Sanchez, M. Calderon; Romero, J. L.; Salur, S.; Haag, B.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构：
[Agakishiev, H.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
摘要：
STAR measurements of dihadron azimuthal correlations (Lambda phi) are reported in midcentral (20-60%) Au + Au collisions at v root sNN = 200 GeV as a function of the trigger particle's azimuthal angle relative to the event plane, phi(s) = | phi(1) -psi(EP)|. The elliptic (v(2)), triangular (v(3)), and quadratic (v(4)) flow harmonic backgrounds are subtracted using the zero yield at mini + Au collisions. It is found that a finite near-side (| Delta phi | < pi/2) long-range pseudorapidity correlation (ridge) is present in the in-plane direction (phi(s) similar to 0). The away-side (| Delta phi | > pi/2) correlation shows a modification from d+ Au data, varying with fs. The modification may be a consequence of path-length-dependent jet quenching and may lead to a better understanding of high-density QCD.
作者：
Agakishiev, G.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A. V.;Alekseev, I.;...
期刊：
PHYSICAL REVIEW C,2012年85(1) ISSN：2469-9985
通讯作者：
Agakishiev, G.
作者机构：
[Kechechyan, A.; Kizka, V.; Agakishiev, G.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Vokal, S.] Joint Inst Nucl Res, Dubna 141980, Russia.;[Underwood, D. G.; Krueger, K.; Bridgeman, A.; Spinka, H. M.] Argonne Natl Lab, Argonne, IL 60439 USA.;[Ullrich, T.; Pile, P.; Lamont, M. A. C.; LeVine, M. J.; Ljubicic, T.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Fine, V.; Fisyak, Y.; Videbk, F.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Sorensen, P.; Christie, W.; Arkhipkin, D.; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Gordon, A.; Landgraf, J. M.; Yip, K.; Didenko, L.; Guryn, W.; Mitrovski, M. K.; Van Buren, G.; Lee, J. H.] Brookhaven Natl Lab, Upton, NY 11973 USA.;[Perkins, C.; Crawford, H. J.; Engelage, J.; Judd, E. G.] Univ Calif Berkeley, Berkeley, CA 94720 USA.;[Sanchez, M. Calderon de la Barca; Mall, O. I.; Draper, J. E.; Cebra, D.; Brovko, S. G.; Sangaline, E.; Reed, R.; Romero, J. L.; Salur, S.; Haag, B.; Liu, H.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构：
[Agakishiev, G.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
摘要：
This paper reports results for directed flow v(1) and elliptic flow v(2) of charged particles in Cu + Cu collisions at root s(NN) = 22.4 GeV at the Relativistic Heavy Ion Collider. The measurements are for the 0-60% most central collisions, using charged particles observed in the STAR detector. Our measurements extend to 22.4-GeV Cu + Cu collisions the prior observation that v1 is independent of the system size at 62.4 and 200 GeV and also extend the scaling of v(1) with eta/y(beam) to this system. The measured v(2)(p(T)) in Cu + Cu collisions is similar for root s(NN) throughout the range 22.4 to 200 GeV. We also report a comparison with results from transport model (ultrarelativistic quantum molecular dynamics and multiphase transport model) calculations. The model results do not agree quantitatively with the measured v(1)(eta), v(2)(p(T)), and v(2)(eta).
作者：
Agakishiev, G.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A. V.;Alekseev, I.;...
期刊：
PHYSICAL REVIEW C,2012年85(1) ISSN：2469-9985
通讯作者：
Agakishiev, G.
作者机构：
[Kechechyan, A.; Kizka, V.; Agakishiev, G.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Vokal, S.] Joint Inst Nucl Res, Dubna 141980, Russia.;[Gliske, S.; Underwood, D. G.; Krueger, K.; Spinka, H. M.] Argonne Natl Lab, Argonne, IL 60439 USA.;[Ullrich, T.; Pile, P.; Lamont, M. A. C.; LeVine, M. J.; Ljubicic, T.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Videbaek, F.; Fisyak, Y.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Sorensen, P.; Christie, W.; Arkhipkin, D.; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Landgraf, J. M.; Yip, K.; Didenko, L.; Guryn, W.; Mitrovski, M. K.; Van Buren, G.; Lee, J. H.] Brookhaven Natl Lab, Upton, NY 11973 USA.;[Perkins, C.; Crawford, H. J.; Engelage, J.; Judd, E. G.] Univ Calif Berkeley, Berkeley, CA 94720 USA.;[Sanchez, M. Calderon de la Barca; Mall, O. I.; Draper, J. E.; Cebra, D.; Brovko, S. G.; Sangaline, E.; Reed, R.; Romero, J. L.; Haag, B.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构：
[Agakishiev, G.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
摘要：
Two-particle azimuthal (Delta phi) and pseudorapidity (Delta eta) correlations using a trigger particle with large transverse momentum (p(T)) in d+Au, Cu+Cu, and Au+Au collisions at root s(NN) = 62.4 GeV and 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider are presented. The near-side correlation is separated into a jet-like component, narrow in both Delta phi and Delta eta, and the ridge, narrow in Delta phi but broad in Delta eta. Both components are studied as a function of collision centrality, and the jet-like correlation is studied as a function of the trigger and associated p(T). The behavior of the jet-like component is remarkably consistent for different collision systems, suggesting it is produced by fragmentation. The width of the jet-like correlation is found to increase with the system size. The ridge, previously observed in Au+Au collisions at root s(NN) = 200 GeV, is also found in Cu+Cu collisions and in collisions at root s(NN) = 62.4 GeV, but is found to be substantially smaller at root s(NN) = 62.4 GeV than at root s(NN) = 200 GeV for the same average number of participants (< N-part >). Measurements of the ridge are compared to models.
作者：
Agakishiev, G.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A. V.;Alekseev, I.;...
期刊：
PHYSICAL REVIEW C,2012年86(1) ISSN：2469-9985
通讯作者：
Agakishiev, G.
作者机构：
[Kechechyan, A.; Kizka, V.; Agakishiev, G.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Vokal, S.] Joint Inst Nucl Res, Dubna 141980, Russia.;[Underwood, D. G.; Krueger, K.; Bridgeman, A.; Spinka, H. M.] Argonne Natl Lab, Argonne, IL 60439 USA.;[Ullrich, T.; Pile, P.; Lamont, M. A. C.; LeVine, M. J.; Ljubicic, T.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Videbaek, F.; Fine, V.; Fisyak, Y.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Sorensen, P.; Christie, W.; Arkhipkin, D.; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Gordon, A.; Landgraf, J. M.; Yip, K.; Didenko, L.; Guryn, W.; Mitrovski, M. K.; Van Buren, G.; Lee, J. H.] Brookhaven Natl Lab, Upton, NY 11973 USA.;[Perkins, C.; Crawford, H. J.; Engelage, J.; Judd, E. G.] Univ Calif Berkeley, Berkeley, CA 94720 USA.;[Sanchez, M. Calderon de la Barca; Mall, O. I.; Draper, J. E.; Cebra, D.; Brovko, S. G.; Sangaline, E.; Reed, R.; Romero, J. L.; Salur, S.; Haag, B.; Liu, H.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构：
[Agakishiev, G.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
摘要：
We present STAR measurements of azimuthal anisotropy by means of the two- and four-particle cumulants nu(2) (nu(2){2} and nu(2){4}) for Au + Au and Cu + Cu collisions at center-of-mass energies root S-NN = 62.4 and 200 GeV. The difference between nu(2){2}(2) and nu(2){4}(2) is related to nu(2) fluctuations (sigma(nu 2)) and nonflow (delta(2)). We present an upper limit to sigma(nu 2)/nu 2. Following the assumption that eccentricity fluctuations sigma(epsilon) dominate nu(2) fluctuations nu(2)/sigma nu(2) approximate to epsilon/sigma epsilon we deduce the nonflow implied for several models of eccentricity fluctuations that would be required for consistency with nu(2){2} and nu(2){4}. We also present results on the ratio of nu(2) to eccentricity.
作者机构：
[Kechechyan, A.; Kizka, V.; Agakishiev, G.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Vokal, S.] Joint Inst Nucl Res, Dubna 141980, Russia.;[Underwood, D. G.; Krueger, K.; Bridgeman, A.; Spinka, H. M.] Argonne Natl Lab, Argonne, IL 60439 USA.;[Jones, P. G.; Nelson, J. M.; Barnby, L. S.] Univ Birmingham, Birmingham, W Midlands, England.;[Ullrich, T.; Pile, P.; Lamont, M. A. C.; LeVine, M. J.; Ljubicic, T.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Videbaek, F.; Fine, V.; Fisyak, Y.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Sorensen, P.; Christie, W.; Arkhipkin, D.; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Gordon, A.; Landgraf, J. M.; Yip, K.; Didenko, L.; Guryn, W.; Mitrovski, M. K.; Van Buren, G.; Lee, J. H.] Brookhaven Natl Lab, Upton, NY 11973 USA.;[Mall, O. I.; Draper, J. E.; Cebra, D.; Brovko, S. G.; Sangaline, E.; Reed, R.; de la Barca Sanchez, M. Calderon; Romero, J. L.; Salur, S.; Haag, B.; Liu, H.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构：
[Agakishiev, G.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
作者：
Agakishiev, G.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A. V.;Alekseev, I.;...
期刊：
PHYSICAL REVIEW C,2012年86(6) ISSN：2469-9985
通讯作者：
Agakishiev, G.
作者机构：
[Kechechyan, A.; Kizka, V.; Agakishiev, G.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Vokal, S.] Joint Inst Nucl Res, Dubna 141980, Russia.;[Underwood, D. G.; Krueger, K.; Spinka, H. M.] Argonne Natl Lab, Argonne, IL 60439 USA.;[Ullrich, T.; Pile, P.; Lamont, M. A. C.; LeVine, M. J.; Ljubicic, T.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Videbaek, F.; Fine, V.; Fisyak, Y.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Sorensen, P.; Christie, W.; Arkhipkin, D.; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Gordon, A.; Landgraf, J. M.; Yip, K.; Didenko, L.; Mitrovski, M. K.; Van Buren, G.; Lee, J. H.] Brookhaven Natl Lab, Upton, NY 11973 USA.;[Perkins, C.; Crawford, H. J.; Engelage, J.; Judd, E. G.] Univ Calif Berkeley, Berkeley, CA 94720 USA.;[Sanchez, M. Calderon de la Barca; Mall, O. I.; Draper, J. E.; Cebra, D.; Brovko, S. G.; Sangaline, E.; Reed, R.; Romero, J. L.; Salur, S.; Haag, B.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构：
[Agakishiev, G.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
摘要：
We present two-dimensional (2D) two-particle angular correlations measured with the STAR detector on relative pseudorapidity eta and azimuth phi for charged particles from Au-Au collisions at root s(NN) = 62 and 200 GeV with transverse momentum p(t) >= 0.15 GeV/c, vertical bar eta vertical bar <= 1, and 2 pi in azimuth. Observed correlations include a same-side (relative azimuth <pi/2) 2D peak, a closely related away-side azimuth dipole, and an azimuth quadrupole conventionally associated with elliptic flow. The same-side 2D peak and away-side dipole are explained by semihard parton scattering and fragmentation (minijets) in proton-proton and peripheral nucleus-nucleus collisions. Those structures follow N-N binary-collision scaling in Au-Au collisions until midcentrality, where a transition to a qualitatively different centrality trend occurs within one 10% centrality bin. Above the transition point the number of same-side and away-side correlated pairs increases rapidly relative to binary-collision scaling, the eta width of the same-side 2D peak also increases rapidly (eta elongation), and the phi width actually decreases significantly. Those centrality trends are in marked contrast with conventional expectations for jet quenching in a dense medium. The observed centrality trends are compared to perturbative QCD predictions computed in HIJING, which serve as a theoretical baseline, and to the expected trends for semihard parton scattering and fragmentation in a thermalized opaque medium predicted by theoretical calculations and phenomenological models. We are unable to reconcile a semihard parton scattering and fragmentation origin for the observed correlation structure and centrality trends with heavy-ion collision scenarios that invoke rapid parton thermalization. If the collision system turns out to be effectively opaque to few-GeV partons the present observations would be inconsistent with the minijet picture discussed here. DOI: 10.1103/PhysRevC.86.064902
