000001663 001__ 1663
000001663 005__ 20190910033754.0
000001663 037__ $$aBELLE2-MTHESIS-2019-005
000001663 041__ $$aeng
000001663 100__ $$aLachlan Vaughan-Taylor
000001663 245__ $$aHigh Energy KL Calibration at Belle II using Initial State Radiation
000001663 260__ $$aSydney$$bThe University of Sydney$$c2019
000001663 300__ $$a118
000001663 500__ $$aPresented on 30 08 2019
000001663 502__ $$aMSc$$bSydney, The University of Sydney$$c2019
000001663 520__ $$aThis thesis presents a feasibility study of a method for KL calibration at the Belle II experiment, using initial state radiation (ISR) production of the KS KL final state. By reconstructing the ISR photon, and the KS and subtracting their energy-momentum 4-vectors from that of the known e+ e− initial state, the 4-vector of the KL may be determined. Due to the loss of second order ISR photons and lost photon energy from incomplete electromagnetic shower reconstruction, a correction is applied to the photon energy. The expected efficiency, after all of the appropriate selections to isolate signal events were applied, was found to be of order 1%. This corresponds to roughly 100 well-reconstructed events per fb−1 of integrated luminosity produced at Belle II, with the difference between the MC generated and reconstructed KL energy found to be of the order of 5 MeV and with the angle between the truth and determined KL vector found to be of the order 0.02 radians=1.1deg. At this production rate, the currently available early Belle II data, which have an integrated luminosity of only 472pb−1 , are likely not large enough for a meaningful KL calibration, however, Belle II is expected to produce 50ab−1 of integrated luminosity. As Belle II produces more data this method will become more and more feasible.
000001663 700__ $$aKevin Varvell$$edir.
000001663 700__ $$aAndrew Bakich$$edir.
000001663 8560_ $$fkevin.varvell@desy.de
000001663 8564_ $$uhttps://docs.belle2.org/record/1663/files/BELLE2-MTHESIS-2019-005.pdf
000001663 980__ $$aTHESIS