# Presentation: 429697

## Simulations Update

- Peter Litchfield

- Update on the Liquid Scintillator analysis
- Comparison Scintillator – RPC
- First look at the totally active detector

## Liquid Scintillator Update

- Nothing very new since the proposal
- Fixed a small number of bugs/problems
- Biggest was to correct the containment volume which had not been changed when the strip length changed from 15.00m to 14.63m  (changed dimensions to feet!!).
- Result was that too few events were being rejected for containment.
- FOM went down because of fewer total events and up because more background than signal is rejected by containment.
- Overall a small reduction (~1.6) in the best FOM1 at 10km after reoptimisation.

## FOM, signal, background v dist

- Off-axis distance (km)

- FOM Events

- 10

- 20

- 30

- Signal
- Background
- FOM

- 40

## Scintillator – RPC Comparison

- Objective:  Fair comparison of the scintillator and RPC detectors.
- Compare a scintillator detector without pulse height to a 1 dimensional readout RPC detector.   Should be directly comparable.
- The gain from pulse height and 2 dimensional readout respectively can then be added to any basic difference.
- Generated Scintillator and RPC data are run through as close as possible identical reconstruction and selection programs.
- Ron and I have exchanged data in the form of x/y,z coordinates.
- The RPC data has run through my reconstruction and analysis system with only very minor changes.
- Ron will report on his analysis of the scintillator data.

## Differences

- The only major difference I have found is that the RPC data has more hit strips and more hits/plane presumably due to the charge spreading on the readout strips
- The containment cut removes a few more events in the RPC data than the scintillator data.
-  partly due to the cross-section area of the RPC detector being slightly smaller
- probably mostly due to the extra hit strips outside the containment volume due to charge spreading
-  Fraction of e CC events kept after reconstruction and containment
- RPC  65%
- Scintillator  69%
- Not optimized for the RPCs, could possibly be improved

## Hit resolutions

- Number of hit strips  for e cc events with 2.0<E<2.2 GeV
- Blue  Scintillator      Red RPC
- Left selected events, Right all events
- Resolution  (RMS/mean)
- RPC All                  22.8%
- RPC selected         12.2%
- Scintillator all          19.5%
- Scintillator selected  9.7%

- Selected events

-       All events

- # strips

## Hits/plane on the Hough track

- RPC

- Scintillator

- More hits/plane on the selected Hough track on the RPC data, slightly better separation on the scintillator data.

-  CC                NC               e CC beam               e CC oscillated

- Hits/plane on Hough track

## Results

|  |  CC | NC  | e beam | Signal | Back
-ground | FOM1 | FOM2 |
| --- | --- | --- | --- | --- | --- | --- | --- |
| RPC          Me
                Ron | 0.5 | 11.2 | 14.5 | 107.6
112        | 26.2
34 | 21.0
19.3 | 9.3 |
| Scintillator Me no PH      Ron | 2.0 | 12.3 | 16.3 | 134.6
123 | 30.6
34 | 24.3
21 | 10.5 |
| Scintillator with PH | 1.8 | 11.3 | 14.7 | 141.0 | 27.8 | 26.8 | 10.8 |

- Each case optimized for the best FOM1.

## Totally Active Detector

- Leon Mualem has generated events in a totally active detector, same types as for the liquid scintillator detector.
- 25 ktons
- 17.5m x 17.5m x 98m
- 1000 x and 1000 y liquid scintillator planes, no absorber
- Scintillator strips 4.9 x 3.9 x 1750 cms
- Read out from one side as in the proposal detector.
- Reconstructed with the same algorithms as for the proposal, only very minor modifications required.
- Analyzed with the same variables and cuts as for the absorber detector

## TA Analysis

- Very preliminary analysis
- Smallish statistics ~300K events/type
- Only training sample, no test sample
- Limited optimization
- Detector 10km off-axis
- 5 years at 3.7 x 1020 pot/year
- Main changes from standard detector
- Pulse height cuts
- Containment region, much smaller as harder to escape unseen from totally active detector

## TA detector plots

## TA detector plots

- Final 2 cuts

- Likelihood cuts

## Results

| Test |  cc | nc | e beam | signal |
| --- | --- | --- | --- | --- |
| Oscillated events | 2874 | 5429 | 114 | 426 |
| Reconstructed events | 2807 | 4234 | 108 | 405 |
| Containment | 1816 | 3317 | 79.4 | 303 |
| Event length | 930 | 2245 | 74.7 | 289 |
| Total ph  | 728 | 427 | 32.1 | 243 |
| Hough fraction | 334 | 65.6 | 18.7 | 156 |
| Hough hits/plane  | 31.2 | 51.3 | 17.6 | 144 |
| Beam angle | 20.3 | 46.4 | 16.8 | 137 |
| Likelihood cut | 1.20  | 5.95 | 9.58 | 87.4 |

|  | Signal | Background | FOM1 | FOM2 |
| --- | --- | --- | --- | --- |
| TA 125kton-year | 87.4 | 16.7 | 21.4 | 8.6 |
| SD 250kton-year | 141.0 | 27.8 | 26.8 | 10.8 |

## e CC event

- epe-p+
- E=2.5GeV
- Ee=1.9GeV
- Ep=1.1GeV
- E=0.2GeV

##  CC event

- n-n+o
- E=2.8 GeV
- E=0.5GeV
- En=1.0GeV
- E+=0.4GeV
- Eo =1.8GeV

## NC event

- Npo
- E=10.6 GeV
- Ep=1.04GeV
- Eo =1.97GeV

## Coherent o event

- NoN
-       e+e-N
- E=9.9GeV
- Ee+=0.1GeV
- Ee-=0.4GeV
- E=2.1GeV

## Comments

- Having scanned a small number of events my guess is that between 1/3 and1/2 of the selected background events are in principle distinguishable from e CC events.
- If we succeeded in doing this by exquisite programming (or scanning), the FOM would be ~30, better than the absorber detector. But we can probably also improve the absorber detector with exquisite programming.
- This analysis is still essentially selecting only quasi-elastic or low-y events.  The selection efficiency is only 29% of reconstructed contained events.
- To do significantly better we would need to recognize e CC events with a significant hadron shower.
- I am sure that this analysis can be improved and thus I suspect that a 25kton totally active detector would have at least equivalent sensitivity to the 50kton detector with absorber.