764 research outputs found
Setups for eliminating static charge of the ATLAS18 strip sensors
Construction of the new all-silicon Inner Tracker (ITk), developed by the
ATLAS collaboration for the High Luminosity LHC, started in 2020 and is
expected to continue till 2028. The ITk detector will include 18,000 highly
segmented and radiation hard n+-in-p silicon strip sensors (ATLAS18), which are
being manufactured by Hamamatsu Photonics. Mechanical and electrical
characteristics of produced sensors are measured upon their delivery at several
institutes participating in a complex Quality Control (QC) program. The QC
tests performed on each individual sensor check the overall integrity and
quality of the sensor. During the QC testing of production ATLAS18 strip
sensors, an increased number of sensors that failed the electrical tests was
observed. In particular, IV measurements indicated an early breakdown, while
large areas containing several tens or hundreds of neighbouring strips with low
interstrip isolation were identified by the Full strip tests, and leakage
current instabilities were measured in a long-term leakage current stability
setup. Moreover, a high surface electrostatic charge reaching a level of
several hundreds of volts per inch was measured on a large number of sensors
and on the plastic sheets, which mechanically protect these sensors in their
paper envelopes. Accumulated data indicates a clear correlation between
observed electrical failures and the sensor charge-up. To mitigate the
above-described issues, the QC testing sites significantly modified the sensor
handling procedures and introduced sensor recovery techniques based on
irradiation of the sensor surface with UV light or application of intensive
flows of ionized gas. In this presentation, we will describe the setups
implemented by the QC testing sites to treat silicon strip sensors affected by
static charge and evaluate the effectiveness of these setups in terms of
improvement of the sensor performance
Elliptic flow of electrons from heavy-flavor hadron decays in Au+Au collisions at 200, 62.4, and 39 GeV
We present measurements of elliptic flow () of electrons from the decays
of heavy-flavor hadrons () by the STAR experiment. For Au+Au collisions
at 200 GeV we report , for transverse momentum
() between 0.2 and 7 GeV/c using three methods: the event plane method
({EP}), two-particle correlations ({2}), and four-particle
correlations ({4}). For Au+Au collisions at = 62.4 and
39 GeV we report {2} for GeV/c. {2} and {4} are
non-zero at low and intermediate at 200 GeV, and {2} is consistent
with zero at low at other energies. The {2} at the two lower beam
energies is systematically lower than at 200 GeV for
GeV/c. This difference may suggest that charm quarks interact less
strongly with the surrounding nuclear matter at those two lower energies
compared to GeV.Comment: Version accepted by PR
Identification and recovery of ATLAS18 strip sensors with high surface static charge
The new all-silicon Inner Tracker (ITk) is being constructed by the ATLAS collaboration to track charged particles produced at the High-Luminosity LHC. The outer portion of the ITk detector will include nearly 18,000 highly segmented and radiation hard silicon strip sensors (ATLAS18 design). Throughout the production of 22,000 sensors, the strip sensors are subjected to a comprehensive suite of mechanical and electrical tests as part of the Quality Control (QC) program. In a large fraction of the batches delivered to date, high surface electrostatic charge has been measured on both the sensors and the plastic sheets between which the sensors are packaged for shipping and handling rigidity. Aggregate data from across QC sites indicate a correlation between observed electrical failures and the sensor/plastic sheet charge build up. To mitigate these issues, the QC testing sites introduced recovery techniques involving UV light or flows of ionizing gas. Significant modifications to sensor handling procedures were made to prevent subsequent build up of static charge. This publication details a precise description of the issue, a variety of sensor recovery techniques, and trend analyses of sensors initially failing electrical tests (IV, strip scan, etc.)
Investigation of pairs in the effective mass region near
The DIRAC experiment at CERN investigated in the reaction
the particle pairs and with relative momentum in the pair system less than 100 MeV/c.
Because of background influence studies, DIRAC explored three subsamples of
pairs, obtained by subtracting -- using time-of-flight (TOF) technique
-- background from initial distributions with sample fractions
more than 70\%, 50\% and 30\%. The corresponding pair distributions in and
in its longitudinal projection were analyzed first in a Coulomb model,
which takes into account only Coulomb final state interaction (FSI) and
assuming point-like pair production. This Coulomb model analysis leads to a
yield increase of about four at MeV/c compared to 100 MeV/c.
In order to study contributions from strong interaction, a second more
sophisticated model was applied, considering besides Coulomb FSI also strong
FSI via the resonances and and a variable distance
between the produced mesons. This analysis was based on three different
parameter sets for the pair production. For the 70\% subsample and with best
parameters, pairs was found to be compared to extracted by means of the Coulomb model. Knowing the efficiency
of the TOF cut for background suppression, the total number of detected
pairs was evaluated to be around , which agrees with
the result from the 30\% subsample. The pair number in the 50\%
subsample differs from the two other values by about three standard deviations,
confirming -- as discussed in the paper -- that experimental data in this
subsample is less reliable
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J/ψ production cross section and its dependence on charged-particle multiplicity in p + p collisions at s=200 GeV
We present a measurement of inclusive J/ψ production at mid-rapidity (|y|<1) in p+p collisions at a center-of-mass energy of s=200 GeV with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The differential production cross section for J/ψ as a function of transverse momentum (p ) for
J/\u3c8 production cross section and its dependence on charged-particle multiplicity in p\u202f+\u202fp collisions at s=200 GeV
We present a measurement of inclusive J/\u3c8 production at mid-rapidity ( |y|<1 ) in p+p collisions at a center-of-mass energy of s=200 GeV with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The differential production cross section for J/\u3c8 as a function of transverse momentum ( pT ) for 0<pT<14 GeV/c and the total cross section are reported and compared to calculations from the color evaporation model and the non-relativistic Quantum Chromodynamics model. The dependence of J/\u3c8 relative yields in three pT intervals on charged-particle multiplicity at mid-rapidity is measured for the first time in p+p collisions at s=200 GeV and compared with that measured at s=7 TeV, PYTHIA8 and EPOS3 Monte Carlo generators, and the Percolation model prediction
Improved measurement of the longitudinal spin transfer to \u39b and \u39b hyperons in polarized proton-proton collisions at s =200 GeV
The longitudinal spin transfer DLL to \u39b and \u39b\uaf hyperons produced in high-energy polarized proton--proton collisions is expected to be sensitive to the helicity distribution functions of strange quarks and anti-quarks of the proton, and to longitudinally polarized fragmentation functions. We report an improved measurement of DLL from data obtained at a center-of-mass energy of s 1a = 200 GeV with the STAR detector at RHIC. The data have an approximately twelve times larger figure-of-merit than prior results and cover |\u3b7|< 1.2 in pseudo-rapidity with transverse momenta pT up to 6 GeV/c. In the forward scattering hemisphere at largest pT, the longitudinal spin transfer is found to be DLL = -0.036 \ub1 0.048 (stat) \ub1 0.013(sys) for \u39b hyperons and DLL = 0.032 \ub1 0.043\,(stat) \ub1 0.013\,(sys) for \u39b\uaf anti-hyperons. The dependences on \u3b7 and pT are presented and compared with model evaluations
Correlation measurements between flow harmonics in Au+Au collisions at RHIC
354Flow harmonics ( vn ) in the Fourier expansion of the azimuthal distribution of particles are widely used to quantify the anisotropy in particle emission in high-energy heavy-ion collisions. The symmetric cumulants, SC(m,n) , are used to measure the correlations between different orders of flow harmonics. These correlations are used to constrain the initial conditions and the transport properties of the medium in theoretical models. In this Letter, we present the first measurements of the four-particle symmetric cumulants in Au+Au collisions at sNN=39 and 200 GeV from data collected by the STAR experiment at RHIC. We observe that v2 and v3 are anti-correlated in all centrality intervals with similar correlation strengths from 39 GeV Au+Au to 2.76 TeV Pb+Pb (measured by the ALICE experiment). The v2 – v4 correlation seems to be stronger at 39 GeV than at higher collision energies. The initial-stage anti-correlations between second and third order eccentricities are sufficient to describe the measured correlations between v2 and v3 . The best description of v2 – v4 correlations at sNN=200GeV is obtained with inclusion of the system's nonlinear response to initial eccentricities accompanied by the viscous effect with η/s>0.08 . Theoretical calculations using different initial conditions, equations of state and viscous coefficients need to be further explored to extract η/s of the medium created at RHIC.openopenAdam, J.; Adamczyk, L.; Adams, J.R.; Adkins, J.K.; Agakishiev, G.; Aggarwal, M.M.; Ahammed, Z.; Ajitanand, N.N.; Alekseev, I.; Anderson, D.M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E.C.; Ashraf, M.U.; Atetalla, F.; Attri, A.; Averichev, G.S.; Bai, X.; Bairathi, V.; Barish, K.; Bassill, A.J.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A.K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L.C.; Bordyuzhin, I.G.; Bouchet, J.; Brandenburg, J.D.; Brandin, A.V.; Brown, D.; Bryslawskyj, J.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J.M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, F.-H.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chattopadhyay, S.; Chen, J.H.; Chen, X.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H.J.; Das, S.; Dedovich, T.G.; Deppner, I.M.; Derevschikov, A.A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J.L.; Dunlop, J.C.; Efimov, L.G.; Elsey, N.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Ewigleben, J.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Federicova, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C.E.; Fulek, L.; Gagliardi, C.A.; Geurts, F.; Gibson, A.; Grosnick, D.; Gunarathne, D.S.; Guo, Y.; Gupta, A.; Guryn, W.; Hamad, A.I.; Hamed, A.; Harlenderova, A.; Harris, J.W.; He, L.; Heppelmann, S.; Heppelmann, S.; Herrmann, N.; Hirsch, A.; Holub, L.; Horvat, S.; Huang, X.; Huang, B.; Huang, S.L.; Huang, T.; Huang, H.Z.; Humanic, T.J.; Huo, P.; Igo, G.; Jacobs, W.W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Judd, E.G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kapukchyan, D.; Kauder, K.; Ke, H.W.; Keane, D.; Kechechyan, A.; Kikoła, D.P.; Kim, C.; Kinghorn, T.A.; Kisel, I.; Kisiel, A.; Kochenda, L.; Kosarzewski, L.K.; Kraishan, A.F.; Kramarik, L.; Krauth, L.; Kravtsov, P.; Krueger, K.; Kulathunga, N.; Kumar, S.; Kumar, L.; Kvapil, J.; Kwasizur, J.H.; Lacey, R.; Landgraf, J.M.; Landry, K.D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J.H.; Li, Y.; Li, W.; Li, X.; Li, C.; Lidrych, J.; Lin, T.; Lisa, M.A.; Liu, Y.; Liu, H.; Liu, F.; Liu, P.; Ljubicic, T.; Llope, W.J.; Lomnitz, M.; Longacre, R.S.; Luo, S.; Luo, X.; Ma, R.; Ma, Y.G.; Ma, G.L.; Ma, L.; Magdy, N.; Majka, R.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H.S.; Matonoha, O.; Mayes, D.; Mazer, J.A.; Meehan, K.; Mei, J.C.; Minaev, N.G.; Mioduszewski, S.; Mishra, D.; Mizuno, S.; Mohanty, B.; Mondal, M.M.; Mooney, I.; Morozov, D.A.; Mustafa, M.K.; Nasim, Md.; Nayak, T.K.; Negrete, J.D.; Nelson, J.M.; Nemes, D.B.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L.V.; Nonaka, T.; Nurushev, S.B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.A.; Olvitt, D.; Page, B.S.; Pak, R.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Pruthi, N.K.; Przybycien, M.; Putschke, J.; Quintero, A.; Radhakrishnan, S.K.; Ramachandran, S.; Ray, R.L.; Reed, R.; Ritter, H.G.; Roberts, J.B.; Rogachevskiy, O.V.; Romero, J.L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N.R.; Sahu, P.K.; Salur, S.; Sandweiss, J.; Schambach, J.; Schmah, A.M.; Schmidke, W.B.; Schmitz, N.; Schweid, B.R.; Seger, J.; Sergeeva, M.; Seto, R.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P.V.; Shao, M.; Shen, W.Q.; Shen, F.; Shi, Z.; Shi, S.S.; Shou, Q.Y.; Sichtermann, E.P.; Sikora, R.; Simko, M.; Singha, S.; Smirnov, D.; Smirnov, N.; Solyst, W.; Sorensen, P.; Spinka, H.M.; Srivastava, B.; Stanislaus, T.D.S.; Stewart, D.J.; Strikhanov, M.; Stringfellow, B.; Suaide, A.A.P.; Sugiura, T.; Sumbera, M.; Summa, B.; Sun, X.M.; Sun, X.; Sun, Y.; Surrow, B.; Svirida, D.N.; Tang, A.H.; Tang, Z.; Taranenko, A.; Tarnowsky, T.; Thäder, J.; Thomas, J.H.; Timmins, A.R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; TomKiel, C.A.; Trentalange, S.; Tribble, R.E.; Tribedy, P.; Tripathy, S.K.; Trzeciak, B.A.; Tsai, O.D.; Tu, B.; Ullrich, T.; Underwood, D.G.; Upsal, I.; Van Buren, G.; Vanek, J.; Vasiliev, A.N.; Vassiliev, I.; Videbæk, F.; Vokal, S.; Voloshin, S.A.; Vossen, A.; Wang, F.; Wang, G.; Wang, Y.; Wang, Y.; Webb, J.C.; Webb, G.; Wen, L.; Westfall, G.D.; Wieman, H.; Wissink, S.W.; Witt, R.; Wu, Y.; Xiao, Z.G.; Xie, W.; Xie, G.; Xu, Z.; Xu, J.; Xu, Q.H.; Xu, Y.F.; Xu, N.; Yang, C.; Yang, S.; Yang, Q.; Yang, Y.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.B.; Zhang, X.P.; Zhang, S.; Zhang, Z.; Zhang, L.; Zhang, J.; Zhang, J.; Zhang, Y.; Zhang, S.; Zhao, J.; Zhong, C.; Zhou, C.; Zhou, L.; Zhu, Z.; Zhu, X.; Zyzak, M.Adam, J.; Adamczyk, L.; Adams, J. R.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Ajitanand, N. N.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Atetalla, F.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Barish, K.; Bassill, A. J.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Brown, D.; Bryslawskyj, J.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, F. -H.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; Dedovich, T. G.; Deppner, I. M.; Derevschikov, A. A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Dunlop, J. C.; Efimov, L. G.; Elsey, N.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Ewigleben, J.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Federicova, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Geurts, F.; Gibson, A.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Harlenderova, A.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Herrmann, N.; Hirsch, A.; Holub, L.; Horvat, S.; Huang, X.; Huang, B.; Huang, S. L.; Huang, T.; Huang, H. Z.; Humanic, T. J.; Huo, P.; Igo, G.; Jacobs, W. W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kapukchyan, D.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kikoła, D. P.; Kim, C.; Kinghorn, T. A.; Kisel, I.; Kisiel, A.; Kochenda, L.; Kosarzewski, L. K.; Kraishan, A. F.; Kramarik, L.; Krauth, L.; Kravtsov, P.; Krueger, K.; Kulathunga, N.; Kumar, S.; Kumar, L.; Kvapil, J.; Kwasizur, J. H.; Lacey, R.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, Y.; Li, W.; Li, X.; Li, C.; Lidrych, J.; Lin, T.; Lisa, M. A.; Liu, Y.; Liu, H.; Liu, F.; Liu, P.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, S.; Luo, X.; Ma, R.; Ma, Y. G.; Ma, G. L.; Ma, L.; Magdy, N.; Majka, R.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H. S.; Matonoha, O.; Mayes, D.; Mazer, J. A.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mizuno, S.; Mohanty, B.; Mondal, M. M.; Mooney, I.; Morozov, D. A.; Mustafa, M. K.; Nasim, Md.; Nayak, T. K.; Negrete, J. D.; Nelson, J. M.; Nemes, D. B.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Quintero, A.; Radhakrishnan, S. K.; Ramachandran, S.; Ray, R. L.; Reed, R.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Salur, S.; Sandweiss, J.; Schambach, J.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Schweid, B. R.; Seger, J.; Sergeeva, M.; Seto, R.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Shen, W. Q.; Shen, F.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Smirnov, D.; Smirnov, N.; Solyst, W.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stewart, D. J.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sugiura, T.; Sumbera, M.; Summa, B.; Sun, X. M.; Sun, X.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, A. H.; Tang, Z.; Taranenko, A.; Tarnowsky, T.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Tomkiel, C. A.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Tu, B.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; Vanek, J.; Vasiliev, A. N.; Vassiliev, I.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, G.; Wang, Y.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xu, Z.; Xu, J.; Xu, Q. H.; Xu, Y. F.; Xu, N.; Yang, C.; Yang, S.; Yang, Q.; Yang, Y.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I. -K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, X. P.; Zhang, S.; Zhang, Z.; Zhang, L.; Zhang, J.; Zhang, J.; Zhang, Y.; Zhang, S.; Zhao, J.; Zhong, C.; Zhou, C.; Zhou, L.; Zhu, Z.; Zhu, X.; Zyzak, M
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