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The focusing mirror system

The focusing mirror system. spherical (elliptical) mirror within gap volume for backward refl. plane mirror just beyond radiator for forward reflections . Minimize detector area (~1 m 2 /sector) interference with FTOF. TOF. Low material budget. Reflecting inside. direct &

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The focusing mirror system

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  1. The focusing mirror system • spherical (elliptical) mirror within gap volume for backward refl. • plane mirror just beyond radiator for forward reflections Minimize detector area (~1 m2/sector) interference with FTOF TOF Low material budget Reflecting inside direct & reflected 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 > 3 10-4 Hit prob

  3. Hybrid ring example: Hit prob > 3 10-3 200 trials per point Aerogel: - n=1.06 - thick. increasing with radius: 2-4-6-8-10 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: 2-4-6-8-10 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: 2-4-6-8-10 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: 2-4-6-8-10 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: 2-4-6-8-10 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: 2-4-6-8-10 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: 2-4-6-8-10 cm 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: 2-4-6-8-10 cm 2-2-10-10-10 cm 3-5-5-10-10 cm 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: 2-4-6-8-10 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) 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

  16. Average N p.e. : Semi-reflective Mirror (UBA) 100 trials per point Aerogel: - n=1.06 - thick. increasing with radius: 6-6-6-10-10 cm Same performance with Increased aerogel thickness Can improve high angles only

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