Beam intensity effects on the \(K^+ \rightarrow \pi^+v\bar{v}\) measurement at NA62

Henshaw, Jack (2024). Beam intensity effects on the \(K^+ \rightarrow \pi^+v\bar{v}\) measurement at NA62. University of Birmingham. Ph.D.

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Abstract

The ultra-rare \(K^+ \rightarrow \pi^+v\bar{v}\) decay, precisely predicted in the Standard Model, is a gateway into exploring new physics at mass scales unattainable at present collider experiments. The NA62 experiment at CERN aims at measuring the branching ratio of the \(K^+ \rightarrow \pi^+v\bar{v}\) decay to a precision of 15% with any deviation from the Standard Model prediction hinting at New Physics.

A Cherenkov detector (CEDAR) is used in NA62 to identify a minority component of particles (kaons) in an unseparated hadron beam. The optical design for a new CEDAR detector optimised to work with hydrogen as radiator gas, Cedar-H, is presented. Cedar-H has been commissioned and installed into NA62 with more than satisfactory performances and a 20% increase in light yield.

The single event sensitivity for the \(K^+ \rightarrow \pi^+v\bar{v}\) decay with data collected in 2021 is computed as B\(_{SES}\) = (5.00 ± 0.13\(_{stat}\)) × 10\(^{−11}\). Studies of each component entering into this figure and their variation with the intensity of the NA62 hadron beam are performed. A new optimal beam intensity to maximise the number of \(K^+ \rightarrow \pi^+v\bar{v}\) events collected is discussed.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):