Measurements of single dissociative diffraction of protons in √s = 13 TeV collisions with the ATLAS experiment

Kendrick, James Andrew (2020). Measurements of single dissociative diffraction of protons in √s = 13 TeV collisions with the ATLAS experiment. University of Birmingham. Ph.D.

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Abstract

The first cross-section measurement of single dissociative diffraction in proton-proton collisions (pp → pX) at √ s = 13 TeV is presented. ATLAS data are used to make the measurement differentially as a function of the squared four momenta transfer (t), the fractional energy loss of the intact proton (ξ) and the observable gap in rapidity space (∆η). ALFA, one of the ATLAS forward spectrometers, is used to tag and reconstruct intact protons giving a direct t measurement. Components of the main ATLAS detector, primarily the Inner Detector, are used to reconstruct the dissociative X system and measure ξ and ∆η.

The fiducial range of the measurement is −4 ≤ log10 ξ ≤ −2 and 0.06 GeV2 ≤ |t| ≤ 0.9 GeV2 . Regge theory is applied to extract the slope parameter and the Pomeron intercept from the unfolded |t| and log10 ξ distributions, respectively. The measured value of the slope parameter governing the exponentially falling t dependence is B = 5.5 ± 0.5 GeV−2 . The measured value of the Pomeron intercept is αP(0) = 1.15 ± 0.13.

Simulation work on the L1CALO upgrade of ATLAS is also presented, studying the design of the e/γ algorithm for the phase-1 upgrade.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):