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Author |
Belle II Collaboration (Adachi, I. et al); Gomis, P.; Marinas, C. |
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Title |
Search for an Invisibly Decaying Z ' Boson at Belle II in e(+)e(-) -> mu(+)mu(-) (e(+/-)mu(-/+)) Plus Missing Energy Final States |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review Letters |
Abbreviated Journal  |
Phys. Rev. Lett. |
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Volume |
124 |
Issue |
14 |
Pages |
141801 - 9pp |
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Abstract |
Theories beyond the standard model often predict the existence of an additional neutral boson, the Z'. Using data collected by the Belle II experiment during 2018 at the SuperKEKB collider, we perform the first searches for the invisible decay of a Z' in the process e(+)e(-) -> mu(+)mu(-) Z' and of a lepton-flavor-violating Z' in e(+) e(-) -> e(+/-)mu(-/+)Z'. We do not find any excess of events and set 90% credibility level upper limits on the cross sections of these processes. We translate the former, in the framework of an L, – L, theory, into upper limits on the Z' coupling constant at the level of 5 x 10(-2) – 1 for M-z' <= 6 GeV/c(2). |
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[Jia, S.; Shen, C. P.; Zhou, X. Y.] Beihang Univ, Beijing 100191, Peoples R China |
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Amer Physical Soc |
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English |
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0031-9007 |
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WOS:000523637800002 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4362 |
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Author |
Belle II Collaboration (Abudinen, F. et al); Gomis, P.; Marinas, C. |
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Title |
Search for Axionlike Particles Produced in e(+)e(-) Collisions at Belle II |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
125 |
Issue |
16 |
Pages |
161806 - 9pp |
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Abstract |
We present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e(+)e(-) -> gamma a, a -> gamma gamma in the mass range 0.2 < m(a) < 9.7 GeV/c(2) using data corresponding to an integrated luminosity of (445 +/- 3) pb(-1). Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength g(a gamma gamma) of ALPs to photons at the level of 10(-3) GeV-1. The limits are the most restrictive to date for 0.2 < m(a) < 1 GeV/c(2). |
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Address |
[Polat, G.; Serrano, J.; Zani, L.] Aix Marseille Univ, CPPM, IN2P3, CNRS, F-13288 Marseille, France |
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Amer Physical Soc |
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0031-9007 |
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Notes |
WOS:000577074900004 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4567 |
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Author |
Belle II Collaboration (Abudinen, F. et al); Marinas, C. |
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Title |
Search for B+ -> K+nu(nu)over-bar Decays Using an Inclusive Tagging Method at Belle H |
Type |
Journal Article |
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Year |
2021 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
127 |
Issue |
18 |
Pages |
181802 - 10pp |
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Abstract |
A search for the flavor-changing neutral-current decay B+ -> K+nu(nu) over bar is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to an integrated luminosity of 63 fb(-1) collected at the Upsilon(4S) resonance and a sample of 9 fb(-1) collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B+ -> K+nu(nu) over bar decay, but also the inclusive properties of the other B meson in the Upsilon(4S) -> B (B) over bar event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B+ -> K+nu(nu) over bar of 4.1 x 10(-5) is set at the 90% confidence level. |
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Address |
[Lautenbach, K.; Polat, G.; Serrano, J.; Zani, L.] Aix Marseille Univ, CPPM, CNRS IN2P3, F-13288 Marseille, France |
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Amer Physical Soc |
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English |
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0031-9007 |
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Notes |
WOS:000712526000010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5020 |
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Author |
Belle II Collaboration (Abudinen, F. et al); Marinas, C. |
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Title |
Precise Measurement of the D-0 and D+ Lifetimes at Belle II |
Type |
Journal Article |
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Year |
2021 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
127 |
Issue |
21 |
Pages |
211801 - 9pp |
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Abstract |
We report a measurement of the D-0 and D+ lifetimes using D-0 -> K-pi(+) and D+ -> K-pi(+)pi(+) decays reconstructed in e(+)e(-) -> c (c) over bar data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy e(+)e(-) collider. The data, collected at center-of-mass energies at or near the (sic)(4S) resonance, correspond to an integrated luminosity of 72 fb(-1). The results, (tau)(D-0) = 410.5 +/- 1.1 (stat) +/- 0.8(syst) fs and tau(D-0) = 1030.4 +/- 4.7 (stat) +/- 3.1 (syst) fs, are the most precise to date and are consistent with previous determinations. |
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Address |
[Lautenbach, K.; Polat, G.; Serrano, J.; Zani, L.] Aix Marseille Univ, CPPM, CNRS IN2P3, F-13288 Marseille, France |
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Amer Physical Soc |
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English |
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Series Volume |
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Edition |
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ISSN |
0031-9007 |
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Expedition |
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Conference |
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Notes |
WOS:000721613700003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5032 |
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Author |
Andricek, L. et al; Lacasta, C.; Marinas, C.; Vos, M. |
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Title |
Intrinsic resolutions of DEPFET detector prototypes measured at beam tests |
Type |
Journal Article |
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Year |
2011 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
638 |
Issue |
1 |
Pages |
24-32 |
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Keywords |
Silicon pixel detector; Detector resolution; Spatial resolution; DEPFET; Beam test |
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Abstract |
The paper is based on the data of the 2009 DEPFET beam test at CERN SPS. The beam test used beams of pions and electrons with energies between 40 and 120 GeV, and the sensors tested were prototypes with thickness of 450 μm and pixel pitch between 20 and 32 μm. Intrinsic resolutions of the detectors are calculated by disentangling the contributions of measurement errors and multiple scattering in tracking residuals. Properties of the intrinsic resolution estimates and factors that influence them are discussed. For the DEPFET detectors in the beam test, the calculation yields intrinsic resolutions of approximate to 1 μm, with a typical accuracy of 0.1 μm. Bias scan, angle scan, and energy scan are used as example studies to show that the intrinsic resolutions are a useful tool in studies of detector properties. With sufficiently precise telescopes, detailed resolution maps can be constructed and used to study and optimize detector performance. |
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Address |
[Dolezal, Z.; Drasal, Z.; Kodys, P.; Kvasnicka, P.; Malina, L.; Scheirich, J.] Charles Univ Prague, Fac Math & Phys, Inst Particle & Nucl Phys, CR-18000 Prague, Czech Republic, Email: peter.kodys@mff.cuni.cz |
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Publisher |
Elsevier Science Bv |
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English |
Summary Language |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Expedition |
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Conference |
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Notes |
ISI:000290082600005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
618 |
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Author |
Marinas, C.; Vos, M. |
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Title |
The Belle-II DEPFET pixel detector: A step forward in vertexing in the superKEKB flavour factory |
Type |
Journal Article |
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Year |
2011 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
650 |
Issue |
1 |
Pages |
59-63 |
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Keywords |
SuperKEKB; Belle-II; DEPFET; Pixel detector; ASIC; Mechanics; Cooling; Resolution |
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Abstract |
An upgrade of the successful asymmetric e(+)e(-) collider in KEK (Tsukuba, Japan) is foreseen by the fall of 2013. This new Super Flavor Factory will deliver an increased instantaneous luminosity of up to L = 8 x 10(35) cm(-2) s(-1), 40 times larger than the current KEKB machine. To exploit these new conditions and provide high precision measurements of the decay vertex of the B meson systems, a new silicon vertex detector will be operated in Belle. This new detector will consist of two layers of DEPFET Active Pixel Sensors as close as possible to the interaction point. DEPFET is a field effect transistor, with an additional deep implant underneath the channel's gate, integrated on a completely depleted bulk. This technology offers detection and an in-pixel amplification stage, while keeping low the power consumption. Under these conditions, thin sensors with small pixel size and low intrinsic noise are possible. In this article, an overview of the full system will be described, including the sensor, the front-end electronics and both the mechanical and thermal proposed solutions as well as the expected performance. |
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Address |
[Marinas, C; Vos, M] CSIC UVEG, IFIC, Inst Fis Corpuscular, Valencia, Spain, Email: Carlos.Marinas.Pardo@cern.ch |
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Elsevier Science Bv |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000295106500015 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
768 |
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Author |
Schreeck, H.; Paschen, B.; Wieduwilt, P.; Ahlburg, P.; Andricek, L.; Dingfelder, J.; Frey, A.; Lutticke, F.; Marinas, C.; Richter, R.; Schwenker, B. |
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Title |
Effects of gamma irradiation on DEPFET pixel sensors for the Belle II experiment |
Type |
Journal Article |
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Year |
2020 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
959 |
Issue |
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Pages |
163522 - 9pp |
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Keywords |
DEPFET; Radiation damage; Particle tracking detectors; Belle II |
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Abstract |
For the Belle II experiment at KEK (Tsukuba, Japan) the KEKB accelerator was upgraded to deliver a 40 times larger instantaneous luminosity than before, which requires an increased radiation hardness of the detector components. As the innermost part of the Belle II detector, the pixel detector (PXD), based on DEPFET (DEpleted P-channel Field Effect Transistor) technology, is most exposed to radiation from the accelerator. An irradiation campaign was performed to verify that the PXD can cope with the expected amount of radiation. We present the results of this measurement campaign in which an X-ray machine was used to irradiate a single PXD half-ladder to a total dose of 266 kGy. The half-ladder is from the same batch as the half-ladders used for Belle II. According to simulations, the total accumulated dose corresponds to 7-10 years of Belle II operation. While individual components have been irradiated before, this campaign is the first full system irradiation. We discuss the effects on the DEPFET sensors, as well as the performance of the front-end electronics. In addition, we present efficiency studies of the half-ladder from beam tests performed before and after the irradiation. |
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Address |
[Schreeck, Harrison; Wieduwilt, Philipp; Frey, Ariane; Schwenker, Benjamin] Georg August Univ Gottingen, Phys Inst 2, Friedrich Hund Pl 1, D-37077 Gottingen, Germany, Email: harrison.schreeck@phys.uni-goettingen.de |
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Elsevier |
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English |
Summary Language |
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ISSN |
0168-9002 |
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Expedition |
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Conference |
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Notes |
WOS:000518368800016 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4316 |
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Author |
Wieduwilt, P.; Paschen, B.; Schreeck, H.; Schwenker, B.; Soltau, J.; Ahlburg, P.; Dingfelder, J.; Frey, A.; Gomis, P.; Lutticke, F.; Marinas, C. |
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Title |
Performance of production modules of the Belle II pixel detector in a high-energy particle beam |
Type |
Journal Article |
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Year |
2021 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
991 |
Issue |
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Pages |
164978 - 15pp |
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Keywords |
DEPFET; DESY testbeam; Pixel detector; Belle II; Vertex detector |
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Abstract |
The Belle II experiment at the Super B factory SuperKEKB, an asymmetric e(+) e(-) collider located in Tsukuba, Japan, is tailored to perform precision B physics measurements. The centre of mass energy of the collisions is equal to the rest mass of the gamma (4S) resonance of m(gamma(4S)) = 10.58 GeV. A high vertex resolution is essential for measuring the decay vertices of B mesons. Typical momenta of the decay products are ranging from a few tens of MeV to a few GeV and multiple scattering has a significant impact on the vertex resolution. The VerteX Detector (VXD) for Belle II is therefore designed to have as little material as possible inside the acceptance region. Especially the innermost two layers, populated by the PiXel Detector (PXD), have to be ultra-thin. The PXD is based on DEpleted P-channel Field Effect Transistors (DEPFETs) with a thickness of only 75 μm. Spatial resolution and hit efficiency of production detector modules were studied in beam tests performed at the DESY test beam facility. The spatial resolution was investigated as a function of the incidence angle and improvements due to charge sharing are demonstrated. The measured module performance is compatible with the requirements for Belle II. |
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Address |
[Paschen, B.; Ahlburg, P.; Dingfelder, J.; Luetticke, F.] Univ Bonn, Phys Inst, Nussallee 12, D-53115 Bonn, Germany, Email: philipp.wieduwilt@phys.uni-goettingen.de; |
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Elsevier |
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English |
Summary Language |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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ISSN |
0168-9002 |
ISBN |
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Notes |
WOS:000686054900010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4941 |
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| Permanent link to this record |
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Author |
Belle-II DEPFET and PXD Collaborations (Wang, B. et al); Marinas, C. |
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Title |
Operational experience of the Belle II pixel detector |
Type |
Journal Article |
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Year |
2022 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
1032 |
Issue |
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Pages |
166631 - 7pp |
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Keywords |
Belle II PXD; DEPFET; Pixel detector; Vertex detector |
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Abstract |
The Belle II experiment at the SuperKEKB accelerator has started its physics data taking with the full detector setup in March 2019. It aims to collect 40 times more e+e- collision data compared with its predecessor Belle experiment. The Belle II pixel detector (PXD) is based on the Depleted P-channel Field Effect Transistor (DEPFET) technology. The PXD plays an important role in the tracking and vertexing of the Belle II detector. Its two layers are arranged at radii of 14 mm and 22 mm around the interaction point. The sensors are thinned down to 75 μm to minimize multiple scattering, and each module has interconnects and ASICs integrated on the sensor with silicon frames for mechanical support. PXD showed good performance during data taking. It also faces several operational challenges due to the high background level from the SuperKEKB accelerator, such as the damage from beam loss events, the drift in the HV working point due to radiation effect, and the impact of the high background. |
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Address |
[Alonso, O.; Dieguez, A.] Univ Barcelona, C Marti Franques 1, Barcelona 08028, Spain, Email: wang@mpp.mpg.de |
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Elsevier |
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English |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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ISSN |
0168-9002 |
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Notes |
WOS:000793768200001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5227 |
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Author |
Liptak, Z. et al; Marinas, C. |
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Title |
Measurements of beam backgrounds in SuperKEKB Phase 2 |
Type |
Journal Article |
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Year |
2022 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
1040 |
Issue |
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Pages |
167168 - 19pp |
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Keywords |
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Abstract |
The high design luminosity of the SuperKEKB electron–positron collider will result in challenging levels of beam-induced backgrounds in the interaction region. Understanding and mitigating these backgrounds is critical to the success of the Belle II experiment. We report on the first background measurements performed after roll-in of the Belle II detector, a period known as SuperKEKB Phase 2, utilizing both the BEAST II system of dedicated background detectors and the Belle II detector itself. We also report on first revisions to the background simulation made in response to our findings. Backgrounds measured include contributions from synchrotron radiation, beam-gas, Touschek, and injection backgrounds. At the end of Phase 2, single-beam backgrounds originating from the 4 GeV positron Low Energy Ring (LER) agree reasonably well with simulation, while backgrounds from the 7 GeV electron High Energy Ring (HER) are approximately one order of magnitude higher than simulation. We extrapolate these backgrounds forward and conclude it is safe to install the Belle II vertex detector. |
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Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5496 |
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