Plans for Alignment/Tolerance Studies Laura Fields 5 December 2019 - - PowerPoint PPT Presentation

Laura Fields 5 December 2019

Plans for Alignment/Tolerance Studies

20 Sept 2019 2

Introduction

• We estimate alignment and focusing-related flux uncertainties by simulating neutrino

fluxes with various alignment parameters changed by their tolerances

• This has been done many times now
• First in 2014, then again for the CDR and most recently by Luke Pickering for the TDR
• These studies are major

undertakings, requiring a lot

• f CPU hours and a lot of disk

space, so we only do them when needed.

• But now we need to do it

again! Luke Pickering

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Why Do a New Alignment Study

• Past studies have been insufficient in various ways
• To conserve disk space, we have often only saved neutrino energy spectra at the near and far

detector

• But now we have a near detector that will sit at many off axis positions
• People have also requested uncertainties versus neutrino angle
• We also need to understand how signals in the muon alcoves change when alignment parameters are

varied

• Near detector group studying beam monitoring wants full flux ntuples, not just energy spectra
• Our understanding of important alignment parameters has evolved with time, and past

studies have not included all variations that we think are important

• The beam design has undergone some significant changes since the last study
• Shortened target
• Small changes to horn design
• Most significant (for muon monitor studies): Simplification of hadron absorber
• So we are preparing for a new round of simulations to simulate alignment tolerance

variations

• Will build a bank of flux tuples that can be used for flux, ND and muon monitor studies
• But we are doing some careful planning so that it hopefully won’t have to be repeated soon
• First step of preparation: establish which parameters we want to simulate

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List of Parameters to Vary

2014 2019 New list is based on brainstorming session with Jim Hylen and me

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Questions

• Some outstanding questions
• What exactly is the uncertainty on POT counting
• Is it from the toroids alone, or are there additional factors here (e.g. detector readout window)
• Should we treat target and horn alignment as independent, or shift them together?
• How to handle baffle scraping
• What ‘baffle scraping’ means: We simulate a gaussian beam. In reality the beam will have non-gaussian
• tails. How much of these tails are hitting the baffle/bafflet and producing neutrinos?
• Have traditionally assumed < .25 % of beam is hitting baffle
• How should this be extrapolated to the new baffle/bafflet configuration

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Next Steps

• Other things to consider before we start simulating:
• How can we store all of the information we need with minimal disk foot print
• See talk from Pierce Weatherly
• What geometry updates do we want to make first
• See talk on Tyler Rehak

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The End