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First look at new MC files. D. A. Petyt 4 th Feb ‘04. First look at reconstruction output from the newly-generated “mock-data” MC files. These contain the following improvements: Generator: NEUGEN v3 with INTRANUKE Detector simulation: DetSim + various geometry improvements
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First look at new MC files D. A. Petyt 4th Feb ‘04 • First look at reconstruction output from the newly-generated “mock-data” MC files. • These contain the following improvements: • Generator: NEUGEN v3 with INTRANUKE • Detector simulation: DetSim + various geometry improvements • Up-to-date NuMI fluxes • I have run Standard Reconstruction on ~20000 events from the new far detector MC file and have compared the results with previous studies. • Some differences in the processing include the use of different ROOT and minossoft versions – not yet clear whether this has a significant effect on the result.
Truth quantities – left: old file, right: new file True neutrino energy Some enhancement evident in this region y distribution New file has a much flatter y distribution – is this an expected result of the recent changes to NEUGEN?
y versus En – top: old file, bottom: new file >4 GeV 2-4 GeV 0-2 GeV 0-2 GeV 2-4 GeV >4 GeV Flatter y distribution implies that NC/CC separation will be more difficult in new MC file
Truth quantities contd. True muon momentum True shower energy No obvious effect of INTRANUKE in this plot – presumably washed out by the change in the y distribution? These differences can be explained by the flatter y distribution in thenew MC file
Some numbers • Track-finding efficiency is higher in the new MC file, at the expense of a much higher probability of finding a track in NC events • What is the cause of this change? • One possible contribution – apparent 8 plane tracking threshold in old file compared to 6 plane threshold in new (see PDF plots later in this talk). However, it seems that this can only partially explain the difference.
PDFs used for event selection – old file CC NC Number of planes in track Fraction of digits in track Track pulse height per plane
PDFs used for event selection – new file Number of planes in track Fraction of digits in track Track pulse height per plane What’s happening in this variable? Why does hit fraction cut off at 0.8?
A closer look at PDF variable #2 Fraction of digits in track, plotted for y<0.2 OLD NEW • Hit fraction for new file seems stuck below 0.8. Why is this? • My guess is that this is due to many low pulse height hits in the event (a.k.a. cross-talk) that are not included in the track. These hits are not present (or are at a much lower level) in the old file
New variable • Since cross-talk hits have low pulse height, a more reasonable track-like estimator in this case is the fraction of total pulse height contained in the track. • The two plots below show the distribution of this variable for CC events in the old file (left) and the new file (right). • The cut-off at 0.8 in the new file is eliminated. The low ‘shoulder’ in the right-hand distribution is more promiment, but this is likely to be a manifestation of the flatter y-distribution in the new file OLD NEW
Summary and future work • The initial conclusions of this study are: • The new MC file has a flatter y-distribution (is this expected from the recent NEUGEN updates?) • NC and CC distributions are less distinct as a result – NC/CC separation will be more difficult (this was also the conclusion of a similar NEUGEN2/NEUGEN3 comparison I did with off-axis MC) • The presence of what I claim are cross-talk hits makes pulse height-based variables preferable to hit-based variables. • No obvious signatures of INTRANUKE effects yet, although the ntuple format is not ideally suited to this (can’t study pion multiplicities for example). • I haven’t looked at event separation/selection efficiencies yet, although this is the logical next step • Expect efficiencies/purities to be somewhat worse for the reasons stated above