# Presentation: 738728

## Monte Carlo Comparison of RPCs and 

**Liquid Scintillator**

- R. Ray
- 5/14/04

-  RPCs with 1-dimensional readout (generated by RR) and liquid scintillator with
- no pulse height (generated by PL/LM) should give similar results.
-  Comparing results serves as a useful cross check for RPC and liquid simulations.
- Detailed description of custom container implemented in GEANT.
-  Plywood absorber
-  12 double gap RPCs modules per container
-  6 RPCs per module (3 wide x 2 deep)
-  5 mm dead space around edge of each RPC
-  X & Y readout strips (can be used as X or Y at analysis stage)
-  Cross-talk between strips included.
-  Using beam file for 820 km, 10 km off-axis.
-  Generating large samples of events on the farm:
-  e
- CC
- NC
-  Beame

## General Strategy

-  Implement custom container description in GEANT.
-  Use  NEUGEN3 event generator with a flat energy distribution
-  Weight interaction vertex in GEANT by number of target
- nucleons in various materials
-  Parabolic fit to multiple tracks in an event.
-  Weight final distributions by evolved beam spectra.

## GEANT Implementation

- Composite *aluminum*
- and particle board
- corner post.  Corner
- blocks included.

**Container Dimensions**
- Length	8.534 m
- Width	2.673 m
- Height	2.438 m

- 1/8 in. *steel* skin

- Composite *steel* and
- particle board
- corner post.  Corner
- blocks included.

- 1/8 in
*aluminum* skin

- RPC module - 3 wide x 2 deep

## Side view

- 12 modules in all
- Modules include 6 RPCs (3 wide by 2 deep)
- Ignore Y strips for odd numbered modules
- Ignore X strips for even numbered modules

- Plywood Absorber
- 11 full layers + 2 half layers
- Full layers 15.24 cm thick, ~28% X0

## 50 kton Detector

- 2 X 8 X 75 Stack of Containers

- x

- y

- z

- 1/2 in. vertical gap between
- RPC modules in adjacent containers
- 3/8 in. horizontal gap between RPC modules in adjacent containers
- RPCs have a 5 mm dead space around outer edge.    1 cm dead space between the set of 3  RPCs in each plane.
- 2 in. gap between containers in Z

## Evolved Neutrino Energy Spectra

- Flat neutrino spectrum
- generated between
- 0.1 - 3.5 GeV for e and
- 0.1 - 20 GeV for 
- and Beam e.
- Weight applied at
- ntuple level.

## Cross Talk (Charge Sharing) Implemented in GEANT

- Based on measurements by Valeri
- on small chambers.

- (cm)

- Cross talk is determined from the probability
-  of a hit on strip 1 for a hit on strip 2 as a
- function of distance from strip 1

- Cross talk is one of the biggest differences between the two technologies

## Cross Talk (cont.)

- One can imagine that cross talk from direct induction goes as the solid angle ...
- For each of the two RPCs:
- Use probability curve on previous page for cross talk on the near readout strip.
- For the far readout strip compress the horizontal axis by a factor of 2, i.e. the
- cross talk at 0.25 cm becomes the cross talk at 0.5 cm.

********1reconstructed track in each view with reasonable 2
-  Total Hits
-  Length of electron candidate track in each view
** **Ave. hits/plane for electron candidate track in each view
-  Fraction of hits on electron candidate track/total hits
** **Hits on electron candidate track in each view
-  No more than 2 hits outside fiducial volume (50 cm in X & Y, 2 m in Z)
**Use the following to form likelihood distributions**
-  Number of hit planes on electron candidate track
-  RMS width distribution of electron candidate track
-  Track angle with respect to beam direction
-  Largest gap in electron candidate track
-  Fraction of hits on electron candidate track/total hits
-  Ave. hits/plane for electron candidate track in each view

## Results

| RPC X or Y |  |  |  |  |
| --- | --- | --- | --- | --- |
|  | e | NC | CC | Beam e |
| Efficiency | 0.13 | 0.002 | 8 x 10-5 | 0.02 |
| # of events | 112 | 19.8 | 1.1 | 13.1 |
| FOM | 19.2 |  |  |  |

| Liquid no ph |  |  |  |  |
| --- | --- | --- | --- | --- |
|  | e | NC | CC | Beam e |
| Efficiency | 0.14 | 0.002 | 0.0001 | 0.02 |
| # of events | 123 | 21.7 | 1.6 | 11.1 |
| FOM | 21.0 |  |  |  |

| RPC X and Y |  |  |  |  |
| --- | --- | --- | --- | --- |
|  | e | NC | CC | Beam e |
| Efficiency | 0.15 | 0.0007 | 7 x 10-7 | 0.024 |
| # of events | 133 | 7.6 | 0.01 | 15.1 |
| FOM | 27 |  |  |  |

**Results**

## Summary

-  RPC X or Y and liquid scint with no pulse height get consistent results.
-  Results are not as good as RPC X and Y or liquid scint with pulse height, as expected.
-  Study does not tell us much about a technology choice, but it would seem to
- 	indicate that no one is making any large blunders
-   Algorithms being used are still somewhat primitive.  More sophisticated algorithms
- 	will be developed over time and efficiencies and FOMs will improve.