# Presentation: 556653

## Paddle Locations*

- 1

- Bkg
- Scint.
- (9”x12”)

- 33”

- 23.5”

- MuID Hole

- Beam
- Pipe

- 2

- Beam View

- Side View, South Arm

- fan in/fan out

- 62ns Delay

- NTC
- FEM

- 10 cm

- 31 ns

- * Commissioned by Xie Wei and Hiro Heijima

## Reason for Delaying Signal

- 1

- 2

- coming from back (early time hits)

- coming from front (in time hits)

- The NTC FEM has an active time window of ~20 ns
- Hits at the paddle coming from the back happen 62 ns before hits coming from the front, and hence the 62 ns delay (so that they arrive at the same time in the NTC FEM active time window).
- The time coverage of the early time and in time signals is

- early time

- in time

## Production on Disk

- Located under
- Runs 126943?, 127099?, 127103, 127105, 127106, 127108, 127110, 127245, 127247, 127249, 127251, 127256
- Triggers: Clock, Forward, Forward&BBCLL1, Forward&MUIDS_1D
- Forward and Clock are prescaled
- Production was very slow due to bug in macro, now fixed (6-7 hours per segment originally, down to 15 minutes per segment).

- /phenix/data37/phnxreco/run4pp_Muon_BKD_v01_pro57
- /phenix/data42/phnxreco/run4pp_Muon_BKD_v01_pro57

## Coincidence Between Paddles

- Hits Coming From Back (Early in Time)

- Paddle 1 TDC

- Paddle 2 TDC

- Paddle 2 TDC

- Paddle 1 TDC

- Paddle 1 TDC

- Paddle 2 TDC

- Paddle 2 TDC

- Paddle 1 TDC

- Clock

- Forward

- Forward&MUIDS_1D

- Forward&BBCLL1

## Coincidence Between Paddles

- Right Time

- Paddle 1 TDC

- Paddle 2 TDC

- Paddle 2 TDC

- Paddle 1 TDC

- Paddle 1 TDC

- Paddle 2 TDC

- Paddle 2 TDC

- Paddle 1 TDC

- Clock

- Forward

- Forward&MUIDS_1D

- Forward&BBCLL1

- Hits Coming From Front (In Time)

## Time Distribution of Background

- Clock
- Forward
- Forward&BBCLL1
- Forward&MUIDS_1D

- Gap from -50 to -10 ns is due to limited size of NTC TDC Window
- Late Hits in BBCLL1 events relative to MUIDS_1D is because the MUIDS_1D comes mostly from muons, while BBCLL1 has lots of hadronic backgrounds
- Evidence for this in ADC Spectrum (in following slides)
- Means Forward&MUIDS_1D selects (probably) muon tracks that go through Muon Arm and hits the forward paddles

- ?

## ADC Dist (for Paddle Coincidence)

- Early1
- Early2
- InTime1
- InTime2

- Large Excess of Hits coming from the Back (Early in Time), factor of about 10.
- Clear MIP seen, on top of an exponential background
- More Background relative to signal for InTime Paddles
- Likely dominated by muons
- Could be expected because of the shielding from forward going particles
- Momentum cut for particles coming from back is much lower than particles from front

## ADC Dist. by Trigger

- Clock

- Forward

- Forward&MUIDS_1D

- Forward&BBCLL1

- early1
- early2
- intime1
- intime2

## Mid-Time ADC Distribution

- InTime1
- InTime2

- Selecting junk outside of incoming bunch and outgoing bunch (in the mid-time region)
- Specifically, cut on hits with -10 to 0 ns.
- Response of Scintillator
- Neutron capture leads to large energy deposit
- responsible for peak at 4095 in mid-time ADC dist?
- How about if we look at hits in only one scintillator, and not the other (right plot)
- Thermal Electrons only leave energy in one scintillator
- Seems that paddle closer to MuID gets more hits

- Early1
- Early2
- InTime1
- InTime2

- Sngl Hit ADC Dist

## ADC Correlation, Back1 vs Back2

## ADC Correlation, Fwd1 vs Fwd2

## Time Dependence of Bkg Scint.

- BBCLL1
- MUIDS_1D&BBCLL1
- Forward&MUIDS_1D
- Forward/10
- Forward&BBCLL1

- Run 127110

- Counts/Fixed number of taken inclusive events
- This is during a test run (not physics), so you can see them playing with the tune
- When BBC rate goes down, the forward rate goes up
- Steered off ideal position, increasing background rate (Forward) while decreasing physics rate (BBCLL1)
- Forward rate is roughly comparable to BBC rate during entire run (small decrease relative to physics triggers, but not too much)
- Early Time Background is there during entire run

## Summary

- We did some complementary studies to what has been done in understanding the non-physics background in the Muon Arms, which are important for planning triggers in the forward region
- Actual measurements of the background using scintillators
- Based on this study, we learn there is the possibility of a large improvement in rejection factor from the use of timing information in a trigger
- Hits from back side come too early in time, and there are about 10X more of them relative to the in time hits (ie, those from a collision or caused forward going beam)
- Our Setup is mostly not sensitive to neutrons (little bit from showering hadrons in material around scintillators).
- Little idea about the behavior of neutron background, though some attempts were made
- Neutrons will have a broad time distribution
- Cut on hits that are in between early fast peak and collision related peaks.
- Neutrons either aren’t seen by scintillators or are captured in one scintillator and have large response
- Look at paddles where one is hit and not the other (but this also picks up thermal electrons, which don’t have enough energy to penetrate both scintillators)
- If neutrons are such a big background, any chance we can study using moderators to help reduce their effect?

## ADC Dist (NOT Coincidence)

- Early1
- Early2
- InTime1
- InTime2

## Noise in Paddle #91?

## Weird ADC values in Back1 (ch13)

- at (tdc0-tdc1)~0, this is when neither tdc fires, but we still get large ADC????
- rest is when both tdc’s fire