Measurements of beam backgrounds in SuperKEKB Phase 2

Liptak, Z.; Paladino, A.; Šantelj, L.; Schueler, J.; Stefkova, S.; Tanigawa, H.; Tsuzuki, N.; Aloisio, A.; Ahlburg, P.; Bambade, P.; Bassi, G.; Baudot, J.; Browder, T. E.; Casarosa, G.; Cautero, G.; Cinabro, D.; Claus, G.; Cuesta, D.; Capua, F. Di; Carlo, S. Di; Flanagan, J.; Frey, A.; Fulsom, B. G.; Funakoshi, Y.; Gabriel, M.; Giordano, Raffaele; Giuressi, D.; Goffe, Mathieu; Hara, K.; Hartbrich, O.; Hedges, M. T.; Heuchel, Daniel; Iida, N.; Ishibashi, Takuya; Jaaskelainen, Kimmo; Jehanno, Didier; Jong, S. de; Kraetzschmar, T. M. G.; Licata, C. La; Lanceri, L.; Leitl, P.; Lewis, P.; Mariñas, C.; Miller, C.; Moser, H. G.; Nakamura, K.; Nakayama, Hiroyuki; Niebuhr, C.; Onuki, Y.; Pang, Chengguo; Paschen, B.; Ripp-Baudot, I.; Rizzo, G.; Roney, J. M.; Schreeck, H.; Schwenker, B.; Simon, F.; Specht, Matthieu; Spruck, B.; Soloviev, Y.; Szelezniak, Michal; Tanaka, S.; Terui, Shinji; Tortone, G.; Tsuboyama, T.; Uematsu, Y.; Vahsen, S. E.; Vitale, L.; Windel, H.

doi:10.1016/j.nima.2022.167168

Cited by 14 publications

(13 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Simulated events are generated using KKMC for quark-antiquark pairs from e + e − collisions [13], Pythia8 for hadronization [3], EvtGen for the decay of the generated hadrons [14], and Geant4 for the detector response [15]. The simulation includes simulated beam-induced backgrounds [16].…”

Section: The Belle II Detector and Samplesmentioning

confidence: 99%

Combined analysis of Belle and Belle II data to determine the CKM angle ϕ3 using B+ → D($$ {K}_S^0 $$h+h−)h+ decays

Abudinén

Aggarwal²,

Ahmed³

et al. 2022

J. High Energ. Phys.

View full text Add to dashboard Cite

We present a measurement of the Cabibbo-Kobayashi-Maskawa unitarity triangle angle ϕ3 (also known as γ) using a model-independent Dalitz plot analysis of B+ → D ($$ {K}_S^0 $$ K S 0 h+h−)h+, where D is either a D0 or $$ \overline{D} $$ D ¯ 0 meson and h is either a π or K. This is the first measurement that simultaneously uses Belle and Belle II data, combining samples corresponding to integrated luminosities of 711 fb−1 and 128 fb−1, respectively. All data were accumulated from energy-asymmetric e+e− collisions at a centre-of-mass energy corresponding to the mass of the Υ(4S) resonance. We measure ϕ3 = (78.4 ± 11.4 ± 0.5 ± 1.0)°, where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is from the uncertainties on external measurements of the D-decay strong-phase parameters.

show abstract

Section: The Belle II Detector and Samplesmentioning

confidence: 99%

Combined analysis of Belle and Belle II data to determine the CKM angle ϕ3 using B+ → D($$ {K}_S^0 $$h+h−)h+ decays

Abudinén

Aggarwal²,

Ahmed³

et al. 2022

J. High Energ. Phys.

View full text Add to dashboard Cite

show abstract

“…As reported in Refs. [10] and [11], agreements between first measurements and optimistic background simulation in 2016 and 2018 were poor, and Data/MC ratios strongly diverged from the unity by several orders of magnitude. Therefore, during the early Phase 3 discussed in this paper, we invested a lot of effort in improving the beam-induced background simulation for a better understanding of beam loss mechanisms in the machine.…”

Section: Simulation Accuracymentioning

confidence: 96%

“…In Belle II, the two main single-beam background components are due to beam-gas and Touschek scattering of circulating charges in the vacuum beam pipe. To disentangle these two sources of particle losses, we employ a so-called heuristic model, which was first introduced in Phase 1 [10], improved in Phase 2 [11], and further refined here. Following the beam-gas and Touschek scattering theories [4,25,59], we model measured observables, largely Belle II detector rates and occupancies (Table 2), as…”

Section: Single-beammentioning

confidence: 99%

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

Natochii¹,

Browder²,

Cao³

et al. 2023

Preprint

View full text Add to dashboard Cite

The Belle II experiment at the SuperKEKB electron-positron collider aims to collect an unprecedented data set of 50 ab −1 to study CP-violation in the B-meson system and to search for Physics beyond the Standard Model. SuperKEKB is already the world's highest-luminosity collider. In order to collect the planned data set within approximately one decade, the target is to reach a peak luminosity of 6.3 × 10 35 cm −2 s −1 by further increasing the beam currents and reducing the beam size at the interaction point by squeezing the betatron function down to β * y = 0.3 mm. To ensure detector longevity and maintain good reconstruction performance, beam backgrounds must remain well controlled. We report on current background rates in Belle II and compare these against simulation. We find that a number of recent refinements have significantly improved the background simulation accuracy. Finally, we estimate the safety margins going forward. We predict that backgrounds should remain high but acceptable until a luminosity of at least 2.8 × 10 35 cm −2 s −1 is reached for β * y = 0.6 mm. At this point, the most vulnerable Belle II detectors, the Time-of-Propagation (TOP) particle identification system and the Central Drift Chamber (CDC), have predicted background hit rates from single-beam and luminosity backgrounds that add up to approximately half of the maximum acceptable rates.

show abstract

“…This was followed by Phase 2 in 2018, with the first collisions with the complete accelerator but with an incomplete detector. Instead of the vertex detector, a dedicated background detector system known as Beast 2 was employed [5].…”

Section: The Superkekb/belle II Program and Plansmentioning

confidence: 99%

The Belle II Upgrade Program

Križan¹

2022

Proceedings of 41st International Conference on High Energy Physics — PoS(ICHEP2022)

View full text Add to dashboard Cite

Measurements of beam backgrounds in SuperKEKB Phase 2

Cited by 14 publications

References 13 publications

Combined analysis of Belle and Belle II data to determine the CKM angle ϕ3 using B+ → D($$ {K}_S^0 $$h+h−)h+ decays

Combined analysis of Belle and Belle II data to determine the CKM angle ϕ3 using B+ → D($$ {K}_S^0 $$h+h−)h+ decays

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

The Belle II Upgrade Program

Contact Info

Product

Resources

About