1. Energy Changes and the IR
M. Sullivan
For
M. Boscolo, K. Bertsche, E. Paoloni, S. Bettoni,
P. Raimondi, et al.
SuperB General Meeting
Perugia, Italy
June 15-20, 2009

2. Energy Changes Initial caveat: I have not spent much time on this
Issue lies with the permanent magnet located on the LER
Off resonance running
We should be able to go off resonance
This is a small enough change that the beta functions should be ok enough

3. Current design

4. More Energy Changes Getting down to the Tau-charm Ecm
If the boost is constant, then we need about 2.5 GeV on 1.4 GeV beam energies
However, we would need to take out the LER PM slices
We can actually get down to these energies but with the PM installed the strength ratios of the twin QD0 magnets has to change and this would ruin the external field cancellation of the QD0 windings
Upshot – the PM magnets would have to come out for Tau-charm running

5. Still other Energy Changes
Other resonance running?
Is there interest in running on the 3S, 2S, 1S or 5S?
Is there interest in doing another energy scan?
If so, we will need to take out the PMs again
We can not move the HER energy alone in this SuperB design like we did with PEP-II
The HER energy is tied to the LER energy by the twin QD0 and QF1 magnets
Detector field change
We will need to lower the detector field some (proportional?) to be able to run at charm threshold energies.

6. Summary
The present IR design with PM slices for the LER can most likely work for off resonance running
However, we can not move the center-of-mass energy down to the Tau-charm region without removing the PMs
We also can not go to the other resonances nor can we do an Ecm energy scan without removing the PMs
The PM option still has an attraction for the optimal SuperB design on the 4S where most of the running will occur

7. Summary (2)
Perhaps a plan where we put together a run of several months of different Ecm running (Tau-charm, other resonances, energy scans)
Then we could have an initial shutdown to remove the PMs and do any other perhaps needed changes to the detector or accelerator
Removing the PMs from a given design changes the energy ratio and hence the boost
Very preliminary work had been started on an IR for the new Frascati design which does not use PMs because of the symmetric beta*s
But upon further thinking about the PM option, I suspect we will probably want to reinstate PMs for best 4S running