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Xe analysis meeting Bartender (Accidental pileup) Nsum3

Xe analysis meeting Bartender (Accidental pileup) Nsum3. R. Sawada 18/Jun/2007. Slide from the previous meeting to remind the procedure. Bartender - accidental pileup in signal region. Introduced rotation of Michel positrons for efficient simulation of accidental pileup

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Xe analysis meeting Bartender (Accidental pileup) Nsum3

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  1. Xe analysis meetingBartender (Accidental pileup)Nsum3 • R. Sawada • 18/Jun/2007

  2. Slide from the previous meeting to remind the procedure Bartender - accidental pileup in signal region • Introduced rotation of Michel positrons for efficient simulation of accidental pileup • It performs the simulation in 1.6 sec/event. 100,000 accidental backups were generated. • Procedure • Distribute RD events and Michel positrons randomly according to specified event rate in 2.5 micro sec. • If total energy deposit in the calorimeter is smaller than a threshold, it repeats the first step until total energy deposit becomes larger than the threshold. • Search the most energetic gamma ray. From time of the gamma ray, it searches a positron whose kinematics meets the trigger condition. • Rotate all Michel decay sub-events in 2.5 micro sec time region so that the selected Michel positron comes around the most energetic gamma ray. The time differences between the gamma and the Michel positron are distributed randomly within specified time window.

  3. Distribution of gamma pileups in accidental backgrounds Cut : Two gamma ray pileup Vertical :Energy of the most energetic gamma in a event Horizontal : Time difference of two gamma rays Type 1 Type 3 Type 2 With Michel rotation With kinematics pre-selection Opening angle > 173 degree Energy deposit in calorimeter > 40 MeV Momentum of positron > 47 MeV Time difference of positron and gamma < 750 psec Event selection: 48 < energy deposit < 54 MeV Without Michel With kinematics pre-selection (looser than trigger) Opening angle > 160 degree Energy deposit in calorimeter > 30 MeV Momentum of positron > 40 MeV Time difference of positron and gamma < 50 nsec Event selection: 48 < energy deposit < 54 MeV Events are classified to three types 1 : RD gamma + Michel positron + gamma (no contribution to trigger) 2 : RD gamma + Michel positron + gamma (contributes to trigger) 3 : RD gamma + RD positron

  4. Almost same as the slide at the previous meeting Bartender - accidental pileup in signal region • Introduced rotation of Michel positrons for efficient simulation of accidental pileup • It performs the simulation in 1.6 sec/event. 100,000 accidental backups were generated. • Procedure • Distribute RD events and Michel positrons randomly according to specified event rate in 2.5 micro sec. • If total energy deposit in the calorimeter is smaller than a threshold, it repeats the first step until total energy deposit becomes larger than the threshold. • Search the most energetic gamma ray. From time of the gamma ray, it searches a positron whose kinematics meets the trigger condition. • Rotate all Michel decay sub-events in 2.5 micro sec time region so that the selected Michel positron comes around the most energetic gamma ray. The time differences between the gamma and the Michel positron are distributed randomly within specified time window. Modified to choose a gamma ray randomly to prevent bias

  5. Nsum3 and dependence (undergoing) • Comparison of nsum and nsum3 • Comparison of nsum2 and nsum3

  6. Nsum and Nsum3 nsum/nsum3 : w nsum/nsum3 : v nsum/nsum3 : u

  7. nsum2 and nsum3 Nsum3 Nsum2 Nsum3 Nsum2 w > 4cm w > 4cm u w w u Nsum2 Nsum3 Nsum3 has less dependence on position than nsum2. While too much correction is done in shallow part. Probably due to two reasons (shower and scintillation photon scattering) w > 4cm w > 4cm v v

  8. Resolution before position dependence correction w > 4cm w > 4cm Nsum2 Nsum3 FWHM = 8.9 % sigma = 3.0 % FWHM = 8.5 % sigma = 3.0 % No significant difference. Resolution after position correction must be studied. There are some room to improve Nsum3 (effective solid angle, use center of shower instead of first conversion point...)

  9. End

  10. Nsum3(total charge corrected with total PMT coverage) C : Normalization factor ( constant ) Ω : Total PMT coverage viewed from reconstructed position N : Number of photons observed by a PMT We could also take into account attenuation and scattering. Detailed study of the result is not done yet. If we increase corrections, several parameters can affect the energy resolution ( position reconstruction, attenuation length estimation, simulation settings...). It is not clear how much we should do correction. Philosophy of this calorimeter is measuring energy without complicated correction. Nsum Nsum2 Nsum3

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