Could CKOV1 become RICH?

1. Simulations2. Sensitive area of the detection plane3. Example of a workable solution4. Geometrical efficiency of the photon detecting plane

5. Conclusion

October 19, 2005

Gh. Grégoire

Contents

Focusing geometries

Non exhaustive ! Very preliminary ! Not optimized

Plane mirror

Spherical mirror

R=-1100 mm

Parabolic mirror

Rcurv=-1500 mm = -1

= 0

Spheroidal mirror

Rcurv= -600 mm along X

Rcurv=-1100 mm along Y

More x-focusing obviously needed !

Goal: Č light produced at the focus to get a parallel beam after reflection and placing the detecting plane perpendicularly (for easy simulation/reconstruction)

400 mm

2

12

00

mm

1200 mm

Simulations

• Momenta 190 to 280 MeV/c ( in steps of 10 MeV/c )

• Gaussian beams x-y = 50 mm

x’-y’ = 25 mrad

From S. Kahn’s presentation, Phone conf. March 31, 2005

• Water radiator 20-mm thick

n=1.33

Index not too high to decrease size of rings

Index not too low to get enough photoelectrons

• (Spheroidal) biconic mirror at 45° (curvatures not optimized)

• Particles Muons, pions and electrons (10 kevts each)

Diameter = 250 mm

3

Full beam

700 mm

700 mm

Muons only

700 mm

700 mm

Pixel size 1 mm x 1 mm

Losses < 5 10-

4

Biconic mirror ( not optimized )

280 MeV/c190 MeV/c

• The detecting plane does not have to be sensitive over the full area

Faint ring due to aberrations …

• For all muon momenta covered by MICE,

For all impact positions and directions at the radiator135 < Radius of Č rings < 275 mm

4

Detection element

Hamamatsu assembly H8711 based on R7600 multianode PMT

Imagine the detection plane is equiped with multianode PMTs like Hamamatsu H7600.

16 pixels 4 x 4 mm eachSquare PM 26 x 26 mm

Just an example ! Not a proposal !

Gain 3.5 106 12 stages bialkali 300 < < 600 nm

5

Detection plane

Annular coverage270 mm < D < 550

mm

6

Detected photons

0

10

20

30

40

50

60

70

80

90

0 20 40 60 80 100

Nr detected photons

Nr of photons reaching the detection plane = 89

(for muons of 280 MeV/c)

assuming 100% light collection efficiency

Average nr of anodes hits = 79

For Cherenkov rings, originating from muons hitting any position on the radiator

Geometrical efficiency =89 % 7

Conclusion

1. One still gets enough photons to determine the radii of the rings

2. Next task:

- a lot of optimization

- detailed studies of aberrations with particles off axis

8

- to ease the simulation and analysis- but aberrations will not destroy the separation possibilities

• check that - separation at analysis level is still acceptable

With a rough granularity of the photon detecting plane

• define a simple algorithm to identify pions from muons

- the choice of a photon detection technique

This is still a feasibility study confirming that CKOV1 could be made RICH

To become a serious design work it needs