-- PeterKammel - 14 Feb 2007 ## TIIE distortions caused by wrong electron effect

## TDIE distortions caused by wrong electron effect

## TIIE distortions caused by wall stop effect

## TDIE distortions caused by wall stop effect

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As explained in Tom's Muon Detector Inefficiency report, there exist
time independent ( **TIIE**) and time dependent ( **TDIE**) inefficiencies
of the entrance muon detectors. Both potentially lead to distortions of the observed time spectrum.

- by histogramming the electron time from a mu' against the time of the primary muon mu, which is detected by the entrance muon counters (
**wrong electron**)

- by accepting a mu stopping in the walls, while the mu' delivers the required stop track in the TPC (
**wall stop**).

TIIE is determined from the muon drift distribution.

TIIE (muSC+muPCX+muPCY) | |

Tom analysis rep | |

Tom corrected ? | 8. |

Steve new analysis rep | 3.2 |

One issue with this determination is the possibility of fake stop signatures in the TPC uncorrelated to the TIIE.

The wrong electron effect on the lifetime was estimated
by Tom with his fast MC, giving -0.2 +- 1.1 Hz for TTIE=34 ppm.
It is hard to confirm that from Tom's report. **It would be interesting to see if Tom can roughly reproduce
Steve's ****MuSC**** only PU spectrum.**

Steve estimate the effect with a zero extrapolation for different
entrance counter combinations and got 2.7 Hz. **As discussed
a larger range of efficiencies provided by different run groups
would be helpful. **Tom claims significant statistical uncertainty in this
value.

Alternatively, Steve determines TIIE of the mPC as a ratio of (muSC+muPCX+muPCY)/muSC with a TPC stop signal. This method might not scale proportional to the total TIIE if the counts are not independent. The resulting extrapolated correction is 0.9 Hz.

Tom's fast MC indicates a significant start time dependence of
the fitted lifetime, which is not observed in the data? Tom pointed out that we don't have enough statistics to see this.

Tom estimates the TDIE from the MuSC deadtime as 126 ppm. As a deadtime of 12 ns is assumed, that should not change the fitted lifetime.

Let us pessimistically assume TIIE= 8 ppm. The probability that a mu' fakes a good TPC stop after mu is TIIE * 0.63 * 21 kHz 0.024 ms = 2.5 ppm

Thus a contribution P(te-tmuSC)* 2.5 ppm is added to the undisturbed time distribution. According Tom's report, the most dangerous components are P(te-mu)= ... + 0.03 exp(-t/854ns) + 0.08 exp (-t/151ns). The total distorting amplitudes are thus are 0.08 ppm for Al and 0.2 ppm for Fe, which should be ok.

According to Tom's estimate TDIE=126 ppm. I.e. the wall stop effect is 15x larger than for the TIIE case. Such a contribution would lead to 10 Hz start time sensitivity of the fitted lifetime.

Steve studies the change of the lifetime both for
muPC and muSC deadtime variations and sees only
small effects. **A start time fit of mSC standard
and 100 ns would be informative.
**But as it stands now, the data does not support
Tom's TDIE estimate.

Topic revision: r2 - 2007-02-14 - PeterKammel

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