1. The focusing mirror system
TOF
Reflecting
inside
direct &
reflected
Low material
budget
Minimize
detector area (~1 m2/sector)
interference with FTOF
spherical (elliptical) mirror within gap volume for backward refl.
plane mirror just beyond radiator for forward reflections
Preliminary studies with mirrors (to reduce instrumented area):
- focalization capabilities shown
- ring patterns for positive and negative mesons at different angles and momenta reconstructed
Different scenarios (refractive index, radiator thickness, mirror geometry) are being explored

2. Hit prob >
Hit prob

3. Hybrid ring example: Hit prob > 3 10-3 Hit prob
200 trials per point
Aerogel:
- n=1.06
- thick. increasing
with radius: cm
Mirror: 14-25o
PMTs: UBA
Hit prob

4. LHp-LHk,p : Mirror 14-25o PMTs: UBA
200 trials per point
Aerogel:
- n=1.06
- thick. increasing
with radius: cm
Low angles more challenging
The same with increased
number of trials
Protons benefit the small
number of unfired PMTs
whit expected signal
(P is small when C=0) -

5. Average N p.e. : Mirror 14-25o PMTs: UBA
200 trials per point
Aerogel:
- n=1.06
- thick. increasing
with radius: cm
N p.e. > 5 for reflected rings
N p.e. > 12 for direct rings

6. Average N p.e. : Mirror 14-25o PMTs: UBA
200 trials per point
Aerogel:
- n=1.06
- thick. increasing
with radius: cm
Mirror is mandatory for positive
hadrons and gives benefit for
negative hadrons at large angles
and small energy
Big dot = studies show
in the previous slide

7. Average N p.e. : PMTs: UBA 200 trials per point Aerogel: - n=1.06
- thick. increasing
with radius: cm
Mirror up to 35o:
Worse for positive hadrons
Better for negative hadrons

8. Average N p.e. : PMTs: UBA 200 trials per point Aerogel: - n=1.06
- thick. increasing
with radius: cm
Mirror up to 35o:
Worse for positive hadrons
Better for negative hadrons

9. Average N p.e. : PMTs: UBA Mirror 14-25o Mirror 14-35o
Worse for positive hadrons
Better for negative hadrons

10. LHp-LHk,p : PMTs: UBA Mirror 14-25o Mirror 14-35o
Worse for positive hadrons
Better for negative hadrons

11. Average N p.e. : Mirror Angle Coverage (UBA)
100 trials per point
Aerogel:
- n=1.06
- thick. increasing with radius: cm
Vedere se le dimensioni sono a partire da PIPE
Vedere come mai ho Npe a piu’ di 25 gradi nel caso pos m25
M35 is acceptanble but slightly
worse for positive and does
not improve at large angles ?!

12. Average N p.e. : Aerogel thickness (UBA)
100 trials per point
Aerogel:
- n=1.06
- thick. increasing with radius: cm cm cm
Mettere specchi sulla :w
pipe!
With 2-10 middle-angles improve
With 3-10 only small angles improve

13. Average N p.e. : Mirror Semi-axes (UBA)
100 trials per point
Aerogel:
- n=1.06
- thick. increasing with radius: cm
Symmetric Ellipsoide
Semi-Axes focalizing onto the
photon detector best in Npe

14. Semi-reflective Mirror
Different dielectric or
thin metalized film to
increase the rflection
coefficient at 0o (normal)
Vedere se mirror parte da PIPE
Angle dependence stays with similar Brewster angle
Here b=atan(n2/n1) ~ 64o

15. Semi-reflective Mirror in Geant 4
R and T defined by n1,n2
Only way so far: fake dielectric material
with refraction index ~ 5 to modify
R/T ratio to fifty-fifty.
Brewster angle ~ 79o
Put at zero
Lobe and Back reflection
Diffusion
Next: Take lobe and remove spike to play
with surface roughness
Vedere se mirror parte da PIPE

16. Average N p.e. : Semi-reflective Mirror (UBA)
100 trials per point
Aerogel:
- n=1.06
- thick. increasing with radius: cm
Vedere se mirror parte da PIPE
Same performance with
Increased aerogel thickness
Can improve high angles only