1. LAV simulation with Geant4
Karim Massri, Sergio Giudici
University of Pisa & INFN
Collaboration Meeting 8/9/2010

2. Outline Aim of the simulation Changes made on NA62MC
The LAV simulated layout
The LeadGlass simulated layout
Hits Time Distribution
Hadron Detection Efficiencies
MIP Simulation-data comparison
Conclusions

3. Residual Gas & GigaTrackers
Aim of the simulation
We used a Geant4 simulation
to estimate the LAV detection efficiency
of several particles (e.g. n, p, K, p, m)
in order to study
Residual Gas & GigaTrackers
related backgrounds

4. Changes made on NA62MC Improved LG optical photons absorption length
Improved optical light guide parameters
Not transparent wrapping (optical photons absorption length = 20 nm)
New leaves in the output tree (e.g. Number of PMTs hit, Number of hits in each PMT, …)
New geometry (Only a 5x5 blocks sector simulated)

5. The LAV simulated layout
Everything as the official geometry but
only 5 layers x 5 blocks simulated
Red circles: light guides, Arrow: beam direction

6. The LeadGlass simulated layout
Everything as the official geometry but
PMTs ARE NOT FULLY SIMULATED!
→ Photocatode only with
nominal Quatum Efficiency
(from Hamamatsu)
1 Hit = 1 Photoelectron emitted

7. Hits Time Distribution
Cutoff at 10 ns
in order to reject photoelectrons produced by chain decays
p → m → e
(too delayed to be relevant experimentally)

8. Hadron Detection Efficiencies
nHits request on the MOST HIT PMT

9. Hadron Detection Efficiencies
nHits request on the MOST HIT PMT

10. Hadron Detection Efficiencies
nHits request on the MOST HIT PMT
nHits request on the MOST HIT PMT
Non zero efficiency
at low momenta
due to K decay!

11. Hadron Detection Efficiencies
nHits request on the MOST HIT PMT
Higher efficiency than
the K+ one due to
Ks regeneration!

12. Fluctuactions are different!
Muon studies
Fluctuactions are different!
Simulation: Statistics (Optical
photons fluctuactions..)
Data: Systematics (different aging of blocks,
different quantum efficiencies..)
from SIMULATION
from LNF
Oven data
24!

13. MIP Detection Efficiency
This value changes
with the threshold!
How does it change?
See next slide..

14. MIP Simulation-data comparison
1 p.e. = 0.2 pC (G=1.288 x 10^6)
Block from Layer 2
LAV TB 2010
(See Paolo V.'s talk)

15. Conclusions We improved the NA62MC simulation of LAV
(with respect to december 2009 version)
We calculated the LAV hadron detection efficiencies for several particles
and different thresholds
We compared the results for muons
with LNF Oven runs & LAV TB 2010 data
finding good agreement!