1. Collective effects in EDM storage ring A.Sidorin, Electron cooling group, JINR, Dubna

2. The ring parameters Beam emittance and tune shift Optimum particle number Intrabeam scattering in EDM ring

3. Ya. K. Semertzidis, 13 January

4. The ring and beam parameters Circumference, m25.798564 Transition gamma 1 (  p = 1) Betatron tunes hor/vert0.650014/ 1.183 Mean beta-functions hor/vert, m6.924971348/ 3.805011264 Mean dispersion, m10.65357261 Deuteron momentum, GeV/c1.5 RF harmonic number40 (~360 MHz) Total number of particles10 12 Number of particles in bunch 2.5  10 10

5. Resonance method of deuteron EDM measurement (Yu. Orlov) The deuteron velocity is modulated with the spin rotation frequency In average the vertical component of spin increases in time proportionally to the EDM:

6. Bunch parameters M. Blaskiewicz Rms momentum spread 3.5  10 -3 Rms bunch length, cm8.11 Effective RF voltage, MV1500 Bunching factor (I mean /I max )0.4

7. Beam emittance and tune shift 95% emittances  mm  mrad hor/vert 90/90 Rms emittances  mm  mrad hor/vert 15/15 Tune shift hor=vert0.0155 Maximum tune-shift for a Gaussian distribution, where  is 95% emittance

8. Limitations for tune shift Betatron motion stability (  Q  0.1) Coherent stability ( ) As in usual rings: To exclude general systematic errors: Fast modulation of the vertical betatron frequency, one half of the beam is operated at tune Peculiarity of EDM experiment:

9. Optimum particle number

10. Intrabeam scattering in EDM ring -Ring is operated over transition energy -Large mean dispersion -Large variations of beta function D=0 z =0 Alfredo Luccio n = 1

11. Heating rates Collision integrals in PRF Bjorken-Mtingwa theory

12. FOM for IBS Over transition energy

13. 1/  x, s -1 0.002189304497 1/  y, s -1 9.221239402E-6 1/  z, s -1 7.765313344E-6 Initial growth rates (BETACOOL program, Martini model)

14. Conclusions Tune spread is limited mainly by method used for systematic correction Tune spread and particle number define the beam emittance Depolarization time depends on the emittance and optimum particle number is determined by statistics Increase of emittance leads to increase of price At optic design FOM for IBS has to be minimized