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The Belle II experiment is a particle physics experiment designed to study the properties of B mesons (heavy particles containing a bottom quark). Belle II is the successor to the Belle experiment, and commissioned at the SuperKEKB^[1] accelerator complex at KEK in Tsukuba, Ibaraki prefecture, Japan. The Belle II detector was "rolled in" (moved into the collision point of SuperKEKB) on April 2017.^[2]^[3] Belle II started taking data in early 2018.^[1] Over its running period, Belle II is expected to collect around 50 times more data than its predecessor mostly due to a 40-fold increase in an instantaneous luminosity provided by SuperKEKB as compared to the previous KEKB accelerator.^[1]

Detector upgrade

Much of the original Belle detector has been upgraded^[4] to cope with the higher instantaneous luminosity provided by the SuperKEKB accelerator.^[1] Close to the beam pipe, the two innermost layers of Belle's silicon vertex detector have been replaced by a depleted field effect transistor (DEPFET) pixel detector, and a larger silicon vertex detector.^[4]^[5] A larger central tracking system, a wire drift chamber, has been installed.^[4] Two new particle identification systems have been installed in the forward endcap (consisting of an aerogel ring-imaging Cherenkov detector)^[4]^[6] and in the barrel (consisting of quartz bars utilising totally internally reflected Cherenkov photons and measuring the time of propagation).^[4]^[7] The original CsI(Tl) electromagnetic calorimeter has been re-used (a new pure CsI calorimeter is being designed for the forward endcap^[8] to be installed at a later stage^[8]^[9]). The calorimeter readout electronics have been upgraded.^[4] Finally, scintillators have been installed in the endcaps and inner layers of Belle's
K⁰
_L and muon detector, the original resistive plate chambers (RPCs) from Belle are reused in the outer layers of the barrel.^[4]^[10]

The target dataset is 50 ab⁻¹ at Belle II^[4] compared to 988 fb⁻¹ (with 711 fb⁻¹ at the Υ(4S) energy) at Belle.^[11]

Timeline

The Belle II data taking is separated into three phases:^[12]

Phase I — completed Feb–June 2016: SuperKEKB commissioning to characterize the beam environment

Phase II — started early 2018, running without the inner silicon-based VXD tracking system to characterize background radiation in the innermost tracking system

Phase III — started 2019: data taking with the complete Belle II detector

On November 22 2018 the Belle II detector was completed with the installation of the VerteX Detector (VXD).^[13] On March 25th 2019 the first collisions of the actual physics program were detected.^[14]

References

^ ^a ^b ^c ^d "SuperKEKB". www-superkekb.kek.jp. Retrieved 2017-04-28.
^ "Belle II Experiment on Twitter". Twitter. Retrieved 2017-05-07.
^ "Belle II rolls in - CERN Courier". cerncourier.com. Retrieved 2017-05-22.
^ ^a ^b ^c ^d ^e ^f ^g ^h Abe, T.; et al. (October 2010). "Belle II Technical Design Report". arXiv:1011.0352 [physics.ins-det].
^ Casarosa, Giulia (2015). "Inner tracking devices at the Belle II experiment". Proceedings, 2015 European Physical Society Conference on High Energy Physics (EPS-HEP 2015) : Vienna, Austria, July 22-29, 2015. p. 255.
^ Nishida, S.; et al. (2014). "Aerogel RICH for the Belle II forward PID". Nuclear Instruments and Methods in Physics Research Section A. 766: 28–31. Bibcode:2014NIMPA.766...28N. doi:10.1016/j.nima.2014.06.061.
^ Inami, Kenji (2014). "TOP counter for particle identification at the Belle II experiment". Nuclear Instruments and Methods in Physics Research Section A. 766: 5–8. Bibcode:2014NIMPA.766....5I. doi:10.1016/j.nima.2014.07.006.
^ ^a ^b Manoni, E.; et al. (2017). "The upgrade of the Belle II forward calorimeter". Nuclear Instruments and Methods in Physics Research Section A. 845: 524–527. Bibcode:2017NIMPA.845..524M. doi:10.1016/j.nima.2016.06.074.
^ "Electromagnetic Calorimeter | Belle II Experiment". belle2.jp. Retrieved 2017-05-07.
^ Aushev, T.; et al. (2015). "A scintillator based endcap K_L and muon detector for the Belle II experiment". Nuclear Instruments and Methods in Physics Research Section A. 789: 134–142. arXiv:1406.3267. Bibcode:2015NIMPA.789..134A. doi:10.1016/j.nima.2015.03.060. S2CID 118613296.
^ Bevan, A. J.; Golob, B.; Mannel, Th; Prell, S.; Yabsley, B. D.; Aihara, H.; Anulli, F.; Arnaud, N.; Aushev, T. (2014-11-01). "The Physics of the B Factories". The European Physical Journal C. 74 (11): 3026. arXiv:1406.6311. Bibcode:2014EPJC...74.3026B. doi:10.1140/epjc/s10052-014-3026-9. ISSN 1434-6044. S2CID 9063079.
^ N.Braun - Hadron Spectroscopy Studies at Belle II
^ @belle2collab (November 22, 2018). "VerteX Detector (VXD) successfully installed in #Belle2. The Belle II detector is now complete!" (Tweet) – via Twitter.
^ Kick-off of the Belle II Phase 3 Physics Run

External links

[:0-1] "SuperKEKB". www-superkekb.kek.jp. Retrieved 2017-04-28.

[2] "Belle II Experiment on Twitter". Twitter. Retrieved 2017-05-07.

[3] "Belle II rolls in - CERN Courier". cerncourier.com. Retrieved 2017-05-22.

[:1-4] ^ ^a ^b ^c ^d ^e ^f ^g ^h Abe, T.; et al. (October 2010). "Belle II Technical Design Report". arXiv:1011.0352 [physics.ins-det].

[5] Casarosa, Giulia (2015). "Inner tracking devices at the Belle II experiment". Proceedings, 2015 European Physical Society Conference on High Energy Physics (EPS-HEP 2015) : Vienna, Austria, July 22-29, 2015. p. 255.

[6] Nishida, S.; et al. (2014). "Aerogel RICH for the Belle II forward PID". Nuclear Instruments and Methods in Physics Research Section A. 766: 28–31. Bibcode:2014NIMPA.766...28N. doi:10.1016/j.nima.2014.06.061.

[7] Inami, Kenji (2014). "TOP counter for particle identification at the Belle II experiment". Nuclear Instruments and Methods in Physics Research Section A. 766: 5–8. Bibcode:2014NIMPA.766....5I. doi:10.1016/j.nima.2014.07.006.

[:2-8] Manoni, E.; et al. (2017). "The upgrade of the Belle II forward calorimeter". Nuclear Instruments and Methods in Physics Research Section A. 845: 524–527. Bibcode:2017NIMPA.845..524M. doi:10.1016/j.nima.2016.06.074.

[9] "Electromagnetic Calorimeter | Belle II Experiment". belle2.jp. Retrieved 2017-05-07.

[10] Aushev, T.; et al. (2015). "A scintillator based endcap K_L and muon detector for the Belle II experiment". Nuclear Instruments and Methods in Physics Research Section A. 789: 134–142. arXiv:1406.3267. Bibcode:2015NIMPA.789..134A. doi:10.1016/j.nima.2015.03.060. S2CID 118613296.

[11] Bevan, A. J.; Golob, B.; Mannel, Th; Prell, S.; Yabsley, B. D.; Aihara, H.; Anulli, F.; Arnaud, N.; Aushev, T. (2014-11-01). "The Physics of the B Factories". The European Physical Journal C. 74 (11): 3026. arXiv:1406.6311. Bibcode:2014EPJC...74.3026B. doi:10.1140/epjc/s10052-014-3026-9. ISSN 1434-6044. S2CID 9063079.

[12] N.Braun - Hadron Spectroscopy Studies at Belle II

[13] @belle2collab (November 22, 2018). "VerteX Detector (VXD) successfully installed in #Belle2. The Belle II detector is now complete!" (Tweet) – via Twitter.

[14] Kick-off of the Belle II Phase 3 Physics Run

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 {{coord|36|9|28|N|140|4|30|E|type:landmark|display=title}}<!--verified on google maps-->
-[[File:KEK Belle II Detector (1).jpg|thumb|right|400px|The opened Belle II detector before installation of the inner tracking detectors.]]
+[[File:KEK Belle II Detector (1).jpg|thumb|right|400px|The opened Belle{{nbsp}}II detector before installation of the inner tracking detectors.]]
-The '''[https://www.youtube.com/watch?v=0S2GUhFcIus Belle II experiment]''' is a [[particle physics]] experiment designed to study the properties of [[B meson]]s (heavy particles containing a [[bottom quark]]). Belle II is the successor to the [[Belle experiment]], and commissioned at the [[SuperKEKB]]<ref name=":0">{{Cite web |url=http://www-superkekb.kek.jp/ |title=SuperKEKB |website=www-superkekb.kek.jp |access-date=2017-04-28}}</ref> [[Accelerator physics|accelerator]] complex at [[KEK]] in [[Tsukuba, Ibaraki|Tsukuba]], [[Ibaraki prefecture]], [[Japan]]. The Belle II detector was "rolled in" (moved into the collision point of SuperKEKB) on April 2017.<ref>{{Cite news |url=https://twitter.com/belle2collab/status/851683547517657088 |title=Belle II Experiment on Twitter |work=Twitter |access-date=2017-05-07 }}</ref><ref>{{Cite web|url=http://cerncourier.com/cws/article/cern/68775|title=Belle II rolls in - CERN Courier|website=cerncourier.com|language=en-GB|access-date=2017-05-22}}</ref> Belle II started taking data in early 2018.<ref name=":0" /> Over its running period, Belle II is expected to collect around 50 times more data than its predecessor mostly due to a 40 factor increase in [[Luminosity (scattering theory)| an instantaneous luminosity]] provided by [[SuperKEKB]] as compared to the previous [[KEKB (accelerator)|KEKB]] accelerator.<ref name=":0" />
+The '''[https://www.youtube.com/watch?v=0S2GUhFcIus Belle{{nbsp}}II experiment]''' is a [[particle physics]] experiment designed to study the properties of [[B meson]]s (heavy particles containing a [[bottom quark]]). Belle{{nbsp}}II is the successor to the [[Belle experiment]], and commissioned at the [[SuperKEKB]]<ref name=":0">{{Cite web |url=http://www-superkekb.kek.jp/ |title=SuperKEKB |website=www-superkekb.kek.jp |access-date=2017-04-28}}</ref> [[Accelerator physics|accelerator]] complex at [[KEK]] in [[Tsukuba, Ibaraki|Tsukuba]], [[Ibaraki prefecture]], [[Japan]]. The Belle{{nbsp}}II detector was "rolled in" (moved into the collision point of SuperKEKB) on April 2017.<ref>{{Cite news |url=https://twitter.com/belle2collab/status/851683547517657088 |title=Belle II Experiment on Twitter |work=Twitter |access-date=2017-05-07 }}</ref><ref>{{Cite web|url=http://cerncourier.com/cws/article/cern/68775|title=Belle II rolls in - CERN Courier|website=cerncourier.com|language=en-GB|access-date=2017-05-22}}</ref> Belle{{nbsp}}II started taking data in early 2018.<ref name=":0" /> Over its running period, Belle{{nbsp}}II is expected to collect around 50 times more data than its predecessor mostly due to a 40-fold increase in [[Luminosity (scattering theory)| an instantaneous luminosity]] provided by [[SuperKEKB]] as compared to the previous [[KEKB (accelerator)|KEKB]] accelerator.<ref name=":0" />
 == Detector upgrade ==
-Much of the original Belle detector has been upgraded<ref name=":1">{{cite arxiv|last=Abe|first=T.|display-authors=etal|date=October 2010|title=Belle II Technical Design Report|eprint=1011.0352|class=physics.ins-det}}</ref> to cope with the higher instantaneous luminosity provided by the SuperKEKB accelerator.<ref name=":0" /> Close to the beam pipe, the two innermost layers of Belle's silicon vertex detector have been replaced by a depleted [[Field-effect transistor|field effect transistor]] (DEPFET) pixel detector, and a larger silicon vertex detector.<ref name=":1" /><ref>{{Cite conference |last=Casarosa |first=Giulia |year=2015 |chapter=Inner tracking devices at the Belle II experiment |chapter-url=https://inspirehep.net/record/1430598 |title=Proceedings, 2015 European Physical Society Conference on High Energy Physics (EPS-HEP 2015) : Vienna, Austria, July 22-29, 2015 |page=255}}</ref> A larger central tracking system – a [[Wire chamber|wire drift chamber]], has been installed.<ref name=":1" /> Two new particle identification systems have been installed in the forward endcap (consisting of an [[aerogel]] [[ring-imaging Cherenkov detector]])<ref name=":1" /><ref>{{Cite journal |last=Nishida |first=S. |display-authors=etal |year=2014 |title=Aerogel RICH for the Belle II forward PID |journal=[[Nuclear Instruments and Methods in Physics Research Section A]] |volume=766 |pages=28–31 |bibcode=2014NIMPA.766...28N |doi=10.1016/j.nima.2014.06.061}}</ref> and in the barrel (consisting of quartz bars utilising [[Total internal reflection|totally internally reflected]] [[Cherenkov radiation|Cherenkov]] photons and measuring the time of propagation).<ref name=":1" /><ref>{{Cite journal |last=Inami |first=Kenji |year=2014 |title=TOP counter for particle identification at the Belle II experiment |journal=[[Nuclear Instruments and Methods in Physics Research Section A]] |volume=766 |pages=5–8 |bibcode=2014NIMPA.766....5I |doi=10.1016/j.nima.2014.07.006}}</ref> The original [[Caesium iodide|CsI]]([[Thallium|Tl]]) electromagnetic [[Calorimeter (particle physics)|calorimeter]] has been re-used (a new pure CsI calorimeter is being designed for the forward endcap<ref name=":2">{{Cite journal |last=Manoni |first=E. |display-authors=etal |year=2017 |title=The upgrade of the Belle II forward calorimeter |journal=[[Nuclear Instruments and Methods in Physics Research Section A]] |volume=845 |pages=524–527 |bibcode=2017NIMPA.845..524M |doi=10.1016/j.nima.2016.06.074}}</ref> to be installed at a later stage<ref name=":2" /><ref>{{Cite web |url=http://belle2.jp/electromagnetic-calorimeter/ |title=Electromagnetic Calorimeter {{!}} Belle II Experiment |website=belle2.jp |access-date=2017-05-07}}</ref>). The calorimeter readout electronics have been upgraded.<ref name=":1" /> Finally, scintillators have been installed in the endcaps and inner layers of Belle's {{Subatomic Particle|K-long0|link=yes}} and muon detector, the original resistive plate chambers (RPCs) from Belle are reused in the outer layers of the barrel.<ref name=":1" /><ref>{{Cite journal |last=Aushev |first=T. |display-authors=etal |year=2015 |title=A scintillator based endcap K<sub>L</sub> and muon detector for the Belle II experiment |journal=[[Nuclear Instruments and Methods in Physics Research Section A]] |volume=789 |pages=134–142 |bibcode=2015NIMPA.789..134A |doi=10.1016/j.nima.2015.03.060|arxiv = 1406.3267 |s2cid=118613296 }}</ref>
+Much of the original Belle detector has been upgraded<ref name=":1">{{cite arxiv|last=Abe|first=T.|display-authors=etal|date=October 2010|title=Belle II Technical Design Report|eprint=1011.0352|class=physics.ins-det}}</ref> to cope with the higher instantaneous luminosity provided by the SuperKEKB accelerator.<ref name=":0" /> Close to the beam pipe, the two innermost layers of Belle's silicon vertex detector have been replaced by a depleted [[Field-effect transistor|field effect transistor]] (DEPFET) pixel detector, and a larger silicon vertex detector.<ref name=":1" /><ref>{{Cite conference |last=Casarosa |first=Giulia |year=2015 |chapter=Inner tracking devices at the Belle II experiment |chapter-url=https://inspirehep.net/record/1430598 |title=Proceedings, 2015 European Physical Society Conference on High Energy Physics (EPS-HEP 2015) : Vienna, Austria, July 22-29, 2015 |page=255}}</ref> A larger central tracking system, a [[Wire chamber|wire drift chamber]], has been installed.<ref name=":1" /> Two new particle identification systems have been installed in the forward endcap (consisting of an [[aerogel]] [[ring-imaging Cherenkov detector]])<ref name=":1" /><ref>{{Cite journal |last=Nishida |first=S. |display-authors=etal |year=2014 |title=Aerogel RICH for the Belle II forward PID |journal=[[Nuclear Instruments and Methods in Physics Research Section A]] |volume=766 |pages=28–31 |bibcode=2014NIMPA.766...28N |doi=10.1016/j.nima.2014.06.061}}</ref> and in the barrel (consisting of quartz bars utilising [[Total internal reflection|totally internally reflected]] [[Cherenkov radiation|Cherenkov]] photons and measuring the time of propagation).<ref name=":1" /><ref>{{Cite journal |last=Inami |first=Kenji |year=2014 |title=TOP counter for particle identification at the Belle II experiment |journal=[[Nuclear Instruments and Methods in Physics Research Section A]] |volume=766 |pages=5–8 |bibcode=2014NIMPA.766....5I |doi=10.1016/j.nima.2014.07.006}}</ref> The original [[Caesium iodide|CsI]]([[Thallium|Tl]]) electromagnetic [[Calorimeter (particle physics)|calorimeter]] has been re-used (a new pure CsI calorimeter is being designed for the forward endcap<ref name=":2">{{Cite journal |last=Manoni |first=E. |display-authors=etal |year=2017 |title=The upgrade of the Belle II forward calorimeter |journal=[[Nuclear Instruments and Methods in Physics Research Section A]] |volume=845 |pages=524–527 |bibcode=2017NIMPA.845..524M |doi=10.1016/j.nima.2016.06.074}}</ref> to be installed at a later stage<ref name=":2" /><ref>{{Cite web |url=http://belle2.jp/electromagnetic-calorimeter/ |title=Electromagnetic Calorimeter {{!}} Belle{{nbsp}}II Experiment |website=belle2.jp |access-date=2017-05-07}}</ref>). The calorimeter readout electronics have been upgraded.<ref name=":1" /> Finally, scintillators have been installed in the endcaps and inner layers of Belle's {{Subatomic Particle|K-long0|link=yes}} and muon detector, the original resistive plate chambers (RPCs) from Belle are reused in the outer layers of the barrel.<ref name=":1" /><ref>{{Cite journal |last=Aushev |first=T. |display-authors=etal |year=2015 |title=A scintillator based endcap K<sub>L</sub> and muon detector for the Belle II experiment |journal=[[Nuclear Instruments and Methods in Physics Research Section A]] |volume=789 |pages=134–142 |bibcode=2015NIMPA.789..134A |doi=10.1016/j.nima.2015.03.060|arxiv = 1406.3267 |s2cid=118613296 }}</ref>
-The target dataset is 50{{nbsp}}[[Barn (unit)|ab]]<sup>−1</sup> at Belle II<ref name=":1" /> compared to 988{{nbsp}}[[Barn (unit)|fb]]<sup>−1</sup> (with 711fb<sup>−1</sup> at the [[B-factory|Υ(4S) energy]]) at Belle.<ref>{{Cite journal|last1=Bevan|first1=A. J.|last2=Golob|first2=B.|last3=Mannel|first3=Th|last4=Prell|first4=S.|last5=Yabsley|first5=B. D.|last6=Aihara|first6=H.|last7=Anulli|first7=F.|last8=Arnaud|first8=N.|last9=Aushev|first9=T.|date=2014-11-01|title=The Physics of the B Factories|journal=The European Physical Journal C|language=en|volume=74|issue=11|pages=3026|doi=10.1140/epjc/s10052-014-3026-9|issn=1434-6044|arxiv = 1406.6311 |bibcode = 2014EPJC...74.3026B |s2cid=9063079}}</ref>
+The target dataset is 50{{nbsp}}[[Barn (unit)|ab]]<sup>−1</sup> at Belle{{nbsp}}II<ref name=":1" /> compared to 988{{nbsp}}[[Barn (unit)|fb]]<sup>−1</sup> (with 711{{nbsp}}fb<sup>−1</sup> at the [[B-factory|Υ(4S) energy]]) at Belle.<ref>{{Cite journal|last1=Bevan|first1=A. J.|last2=Golob|first2=B.|last3=Mannel|first3=Th|last4=Prell|first4=S.|last5=Yabsley|first5=B. D.|last6=Aihara|first6=H.|last7=Anulli|first7=F.|last8=Arnaud|first8=N.|last9=Aushev|first9=T.|date=2014-11-01|title=The Physics of the B Factories|journal=The European Physical Journal C|language=en|volume=74|issue=11|pages=3026|doi=10.1140/epjc/s10052-014-3026-9|issn=1434-6044|arxiv = 1406.6311 |bibcode = 2014EPJC...74.3026B |s2cid=9063079}}</ref>
 [[File:Belle II CDC Construction.jpg|thumb|350px|Construction work on the Central Drift Chamber (CDC) of the Belle II experiment.]]
 == Timeline ==
-The Belle II data taking is separated into three phases:<ref>[https://indico.nucleares.unam.mx/event/1180/session/11/contribution/76 N.Braun - Hadron Spectroscopy Studies at Belle II]</ref>
+The Belle{{nbsp}}II data taking is separated into three phases:<ref>[https://indico.nucleares.unam.mx/event/1180/session/11/contribution/76 N.Braun - Hadron Spectroscopy Studies at Belle II]</ref>
-* Phase I — completed Feb-June 2016: SuperKEKB commissioning to characterize the beam environment
+* Phase I — completed Feb–June 2016: SuperKEKB commissioning to characterize the beam environment
 * Phase II — started early 2018, running without the inner silicon-based VXD tracking system to characterize background radiation in the innermost tracking system
-* Phase III — started 2019: data taking with the complete Belle II detector
+* Phase III — started 2019: data taking with the complete Belle{{nbsp}}II detector
-On November 22 2018 the Belle II detector was completed with the installation of the VerteX Detector (VXD).<ref>{{cite tweet|number=1065543351569735681|user=belle2collab|title=VerteX Detector (VXD) successfully installed in #Belle2. The Belle II detector is now complete!<!-- full text of tweet that Twitter returned to the bot (excluding links) added by TweetCiteBot. This may be better truncated or may need expanding (TW limits responses to 140 characters) or case changes. --> |date=22 November 2018}}</ref> On March 25th 2019 the first collisions of the real physics program could be detected.<ref>[https://www.kek.jp/en/newsroom/2019/03/25/2030/ Kick-off of the Belle II Phase 3 Physics Run]</ref>
+On November 22 2018 the Belle{{nbsp}}II detector was completed with the installation of the VerteX Detector (VXD).<ref>{{cite tweet|number=1065543351569735681|user=belle2collab|title=VerteX Detector (VXD) successfully installed in #Belle2. The Belle II detector is now complete!<!-- full text of tweet that Twitter returned to the bot (excluding links) added by TweetCiteBot. This may be better truncated or may need expanding (TW limits responses to 140 characters) or case changes. --> |date=22 November 2018}}</ref> On March 25th 2019 the first collisions of the actual physics program were detected.<ref>[https://www.kek.jp/en/newsroom/2019/03/25/2030/ Kick-off of the Belle II Phase 3 Physics Run]</ref>
 ==See also==
@@ Line 31: / Line 31: @@
 ==External links==
 {{Commonscat}}
-*[http://belle2.jp/ Belle II public webpage]
+*[http://belle2.jp/ Belle{{nbsp}}II public webpage]
-*[https://www.belle2.org/ Belle II collaboration webpage]
+*[https://www.belle2.org/ Belle{{nbsp}}II collaboration webpage]
 *[https://www.youtube.com/watch?v=nGCrrgXSEOk&t=19s A Search for New Physics - The Belle II Experiment]
 *[https://inspirehep.net/record/1108235 Belle II on Inspire]