1. Hall A Pressurized Gas Cerenkov Design Goals:  Separate  and K for p>2.3GeV/c.  Continue to differentiate e/  Features:  Operates at pressures up to 10 psig, using C 4 F 10 or CO 2 as the radiator.  Expect average of 10 p.e. for a 2.3GeV/c pion with C 4 F 10   rejection factor of 400 (3 p.e. cutoff) Experiments:Pentaquark (E05-009), Transversity SSA (E03-004), Flavor Asymmetry in SIDIS (PR04-114 cond. app.) Design and fabrication in collaboration with: Argonne National Laboratory, Rutgers University, and Jefferson Lab

2. Design performance

3. Design (cont) Control cost and effort by re-using optics from present cerenkov. Can the present box be re-used? What modifications are necessary? Finite element analysis by Ravi Anumagalla

4. Design performance

5. Model 4: No top and Bottom faces, includes a “C” Channel on one face Max Stress : 263 ksi Max Deflection : 1.59 inches Boundary Conditions: Pressure on all faces (14.7 psi), Fixed at the bottom and top surface,

6. Model 4: Plot shows surfaces where stresses are in the range of 0-23 ksi

8. Design (cont) Control cost and effort by re-using optics from present cerenkov. Can the present box be re-used? What modifications are necessary? Finite element analysis by Ravi Anumagalla –Weight goes from 750lbs to ~2200lbs. Another idea by Bogdan: titanium cylinder with interior supports (being priced now)

9. Bogdan’s concept

10. Common features PMT sealed against interior for servicing while the chamber is pressurized. Simple stationary gas system since it will be filled from the Hall B gas system. Size is compatible with current short cerenkov. Low-number of knock-on electrons for 0.4mm Ti window (<2%).

11. 0.36%

12. Conclusion Pressurized Cerenkov design continuing. Should provide excellent pi/K separation for momenta greater than 2.3 GeV/c Need to finalize the design (after cost estimates are made)

13. R ich  /K separation for p > 2.5 GeV/c Radiator C6F14 n=1.29  Ch ~ 5mr Radiator C5F12 n=1.24  Ch ~ 5mr 4  separation at ~ 2.5 GeV/c4  separation at ~ 3.0 GeV/c Mauro Iodice – R ICH2004 - Playa del Carmen, Mexico - Nov.30 Dec. 5, 2004

14. R ich  /K separation with C5F12 (n=1.24) radiator (14 cm proximity gap) >20  separation at ~ 2 GeV/c ~ 4  separation at 3.0 GeV/c Mauro Iodice – R ICH2004 - Playa del Carmen, Mexico - Nov.30 Dec. 5, 2004 M onte C arlo Simulations