1. Francesco Forti SuperB Workshop LNF, 16-18 March, 2006
Detector WG
Francesco Forti
SuperB Workshop
LNF, March, 2006

2. A SuperB Detector Basic conclusion from December Workshop:
It is possible to reuse large parts of Babar and Belle with relatively minor technology changes
Detector components
Silicon vertex, with small radius pixels, essential for reduced boost.
Drift chamber
DIRC style PID, with improved readout
CsI(Tl) calorimeter in barrel, something faster (LYSO) in endcap
Existing coil
LST style muon detectors
March 17, 2006
F.Forti - Detector WB

3. Issue number 0 Beam parameters
Current and Collision frequency vary wildly in different designs
Was mA and 1MHz in december
Raimondi – Round with extraction: 100 mA and 10 MHz
Raimondi – Flat(3) uncompressed: 1600mA and 500 MHz
Seeman – 4500 mA and 68 MHz
Different options have very large impact on technology choices and on the reusability of Babar and Belle components.
March 17, 2006
F.Forti - Detector WB

4. Collision frequency
With 0.1-1MHz fc one could exploit the beam crossing time structure to relax detector constraints
Drift time
Electronics shaping time
Crystal decay time
One the other hand a low fc implies overlapping events (mainly Bhabha)
The 10-50MHz regime is the LHC electronics area
It might be possible to exploit the bx time structure, but is it useful ?
At high fc (>100MHz) back to current BFactories operation mode
Continuous beam, no bx information
no pileup
March 17, 2006
F.Forti - Detector WB

5. Current Two consequences of higher currents:
higher background in the detector
occupancy
radiation damage
power dissipation in the beampipe requires water cooling
more material
larger radius
March 17, 2006
F.Forti - Detector WB

6. Types and level of backgrounds
Beam gas
Synchroton radiation
 Both proportional to current
Should not be a problem at Superb
They become a problem at higher currents
Luminosity sources (eg radiative Bhabhas)
Careful IR design. Bhabhas into the detector are there.
Beam-beam interactions
Potentially important
Touschek background
1/E2. Improves with smaller asymmetry. But, much higher beam density
Thermal outgassing
Due to HOM losses. Not an issue with small currents
Injection background
Not an issue because of damping rings scheme
Maybe not true anymore with the 1 collision/turn scheme
Bursts
Due to dust. No real cure. Need robustness of detector
March 17, 2006
F.Forti - Detector WB

7. Background bottom line
Probably reasonable to assume background is not larger than what with have today
Cannot claim a large background reduction with present schemes
Need to design a robust detector with the enough segmentation and radiation hardness to withstand surprises (x5 safety margin)
IR design is critical
Radiative Bhabhas
Syncrotron radiation shielding
Shielding from beam-beam blow up
March 17, 2006
F.Forti - Detector WB

8. Issue number 1 Boost lower boost advantegeous for machine design
Babar: βγ=0.56
Belle: βγ=0.45
SuperB?: βγ=0.28
we can afford to have a lower boost only if the vertexing resolution is good:
small radius beam pipe
very little material in b.p. and first layer
if not, then we should stay with higher boost (0.45)
March 17, 2006
F.Forti - Detector WB

9. Separation significance
<Dz>/s(Dz) vs bg
March 17, 2006
F.Forti - Detector WB

10. Detector components Vertexing Intermediate tracking Central tracking
Thin pixel layer glued on beam pipe
Good aspect ratio for small radius (compared to strips)
Improves patter recognition robustness
needs R&D
Intermediate tracking
Strip detectors
More or less like the current detectors
Reduction in thickness would be desirable, but not essential
Central tracking
Drift chamber
Solid state tracking not performant at low momentum
Need to optimize cell size against occupancy
Belle has developed a fast gas small cell DCH, but with a degraded resolutions
March 17, 2006
F.Forti - Detector WB

11. Detector components PID Calorimeter Muon Trigger/DAQ
Čerenkov based PID – like DIRC
Need development on readout
Fast focusing DIRC
TOP
Endcap region requires special study
Calorimeter
Barrel part could be reused (see other talks)
In the endcaps require smaller Moliere radius and faster crystals  LYSO
Higher currents and smaller Bhabha pileup may change this conclusion
Muon
It doesn’t seem to be a problem
Trigger/DAQ
Calorimeter and/or tracking information
Not substantially different from current schemes.
March 17, 2006
F.Forti - Detector WB