Study of thermal neutron flux from SuperKEKB in the Belle II commissioning detector

Show simple item record

dc.contributor.author Dejong, Samuel Rudy
dc.date.accessioned 2017-05-31T15:06:15Z
dc.date.available 2017-05-31T15:06:15Z
dc.date.copyright 2017 en_US
dc.date.issued 2017-05-31
dc.identifier.uri http://hdl.handle.net/1828/8203
dc.description.abstract The Belle II detector is designed to collect data from the high luminosity electron-positron (e$^+$e$^-$) collisions of the SuperKEKB collider. It will explore the flavour sector of particle physics through precision measurements. The backgrounds of particles induced by the electron and positron beams will be much higher than in any previous \epem collider. It is important that these backgrounds be well understood in order to ensure appropriate measures are taken to protect the Belle II detector and minimize the impact of the backgrounds. In February 2016 electron and positron beams were circulated through the two 3 km vacuum pipe rings without being brought into collision during `Phase I' of SuperKEKB commissioning. Beam backgrounds were measured using Belle II's commissioning detector, BEAST II. BEAST II is composed of several small subdetectors, including helium-3 thermal neutron detectors. The BEAST II thermal neutron detector system and results from its Phase I running are presented in this dissertation. The Phase I experiment studies beam-gas interactions, where beam particles collide with residual gas atoms in the beampipes, and beam-beam interactions, where beam particles interact with each other. Simulations of these two types of backgrounds were performed using the Strategic Accelerator Design (SAD) and GEometry And Tracking (GEANT4) software packages. A method to account for the composition of the gas in the beampipes was developed in order to correctly analyse the beam-gas component of the background. It was also determined that the thermal neutron rates in the data on the positron beam were 2.18$^{+0.44}_{-0.42}$ times higher than the simulation of beam-gas interactions and 2.15$^{+0.34}_{-0.33}$ times higher for beam-beam interactions. The data on the electron beam were 1.32$^{+0.56}_{-0.36}$ times higher for beam-gas interactions and 1.91$^{+0.54}_{-0.48}$ time higher for beam-beam interactions. The impact of these studies on Belle II is discussed. en_US
dc.language English eng
dc.language.iso en en_US
dc.rights Available to the World Wide Web en_US
dc.rights.uri http://creativecommons.org/licenses/by-nc/2.5/ca/ *
dc.subject Physics en_US
dc.subject particle physics en_US
dc.subject Belle II en_US
dc.subject BEAST II en_US
dc.subject Helium-3 en_US
dc.subject Thermal neutrons en_US
dc.subject Beam Background en_US
dc.title Study of thermal neutron flux from SuperKEKB in the Belle II commissioning detector en_US
dc.type Thesis en_US
dc.contributor.supervisor Roney, J. Michael
dc.degree.department Department of Physics and Astronomy en_US
dc.degree.level Doctor of Philosophy Ph.D. en_US
dc.description.scholarlevel Graduate en_US

Files in this item

The following license files are associated with this item:

This item appears in the following Collection(s)

Show simple item record

Available to the World Wide Web Except where otherwise noted, this item's license is described as Available to the World Wide Web

Search UVicSpace


My Account