Presentation on theme: "Accelerator M. Biagini, LNF-INFN on behalf of the SuperB & DA NE Teams 3 rd International Workshop on "B Factories and New Measurements" Atami, Jan."— Presentation transcript:
Accelerator M. Biagini, LNF-INFN on behalf of the SuperB & DA NE Teams 3 rd International Workshop on "B Factories and New Measurements" Atami, Jan. 24 th, 2008 & DA NE crab waist experiment
Outline How to increase Luminosity? The new collision scheme SuperB beam-beam simulations SuperB parameters, layout, lattice DA NE upgrade with new scheme DA NE commissioning status Conclusions
SuperB Accelerator Contributors M. E. Biagini, M. Boscolo, A. Drago, S. Guiducci, M. Preger, P. Raimondi, S. Tomassini, C. Vaccarezza, M. Zobov (INFN/LNF, Italy) Y. Cai, A. Fisher, S. Heifets, A. Novokhatski, M.T. Pivi, J. Seeman, M. Sullivan, U. Wienands (SLAC, US) T. Agoh, K. Ohmi, Y. Onhishi (KEK, Japan) I. Koop, S. Nikitin, E. Levichev, P. Piminov, D. Shatilov (BINP, Russia) A.Wolski (Liverpool University, UK) B.M. Venturini (LBNL, US) S. Bettoni (CERN, Geneva) A. Variola (LAL/Orsay, France) E. Paoloni (Pisa University, Italy)
Increase beam currents Decrease y * Decrease bunch length HOM in beam pipe overheating, instabilities, power costs Detector backgrounds increase Chromaticity increase smaller dinamic aperture RF voltage increase costs, instabilities “Brute force” method How to increase L ? But...
Hourglass effect Bunch length y*y* To squeeze the vertical beam dimensions, and increase L, y at IP must be decreased. This is efficient only if at the same time the bunch length is shortened to y value, or particles in the head and tail of the bunch will see a larger y.
Ultra-low emittance (ILC-DR like) Very small at IP Large crossing angle “Crab Waist” scheme Small collision area Lower is possible NO parasitic crossings NO synchro-betatron resonances due to crossing angle P. Raimondi’s: to focus more the beams at IP and have a “large” crossing angle large Piwinski angle A new idea for L increase Test at DA NE now !!!
Large crossing angle, small x-size Vertical waist has to be a function of x: Z = 0 for particles at – x (- x /2 at low current) Z = x / for particles at + x ( x /2 at low current) (1) and (2) have same Luminosity, but (2) has longer bunches and smaller x 1) Head-on, Short bunches 2) Large crossing angle, long bunches YY Overlap region zz xx zz xx y waist can be moved along z with a sextupole on both sides of IP at proper phase “Crab Waist” Large Piwinski angle: = tg( z / x
Higher luminosity with same currents and bunch length: Beam instabilities are less severe Manageable HOM heating No coherent synchrotron radiation of short bunches No excessive power consumption Lower beam-beam tune shifts Relatively easier to make small x w.r.t. short z Parasitic collisions becomes negligible due to higher crossing angle and smaller x... and...
IP beam distributions for KEKB IP beam distributions for SuperB KEKBSuperB I (A)1.72. y * (mm) 60.2 x * (mm) y * ( m) x * ( m) 806 z (mm) 65 L (cm -2 s -1 )1.7 x x Here is Luminosity gain Beams are focused in the vertical plane 100 times more than in the present factories, thanks to: - small emittances - small beta functions - larger crossing angle Tune shifts and longitudinal overlap are greatly reduced
Luminosity and blow-up vs current M. Zobov
Luminosity vs tunes scan (horizontal axis - x from 0.5 to 0.65; vertical axis – y from 0.5 to 0.65) Individual contours differ by 10% in luminosity Design luminosity can be obtained over a wide tune area P. Raimondi, D. Shatilov, M. Zobov
Transparency condition Due to the large crossing angle, new conditions are possible, different from asymmetric currents, for having equal tune shifts with asymmetric energies LER and HER beams can have different emittances and * and equal currents Present B-factoriesSuperB
LER beam: sees a shorter overlap region, (4/7 of the HER one) has a smaller y *, easier to achieve in the FF w.r.t. HER has larger emittance: better for Touschek lifetime, and tolerance for LER instabilities e+e+ e-e- LER z HER z
SuperB parameters (1) Present parameter set based on ILCDR-like parameters Same DR emittances Same DR bunch length 1.5 times DR bunch charges Same ILC-IP betas Crossing angle and “crab waist” to maximize luminosity and minimize blowup Presently under test at DA NE Use PEP-KEK DR damping time 19 ms No “emittance” wigglers used in Phase 1
SuperB parameters (2) ILC/FFTB like Final Focus Design based on recycling all PEP-II hardware, Bends, Quads and Sexts, and RF system Corresponds to a lot of money ! Maximize Luminosity keeping low wall power: Total power: 17 MW, lower than PEP-II Simulations performed in many labs and with different codes: LNF,BINP,KEK,LAL,CERN
Circumference (m)1800. Energy (GeV) (LER/HER)4/74/7 Current (A)/beam2. No. bunches1342 No. part/bunches5.5x10 10 (rad) 2x24 x (nm-rad) (LER/HER) 2.8/1.6 y (pm-rad) (LER/HER) 7/47/4 y * (mm) (LER/HER) 0.22/0.39 x * (mm) (LER/HER) 35/20 y * ( m) (LER/HER) x * ( m) (LER/HER) 10/6 z (mm) 5 Power (MW)17 L (cm -2 s -1 )1.x10 36 SuperB Parameters (Phase 1) Transparency conditions
Ring Layout Length 20 m Total length ~1800 m Length 280 m HER No polarization section here
Crossing angle to 2*25 mrad, L*=0.4 m Local chromaticity correction Horiz.beam separation at QD0: 2 cm, about 180 x A possible solution with a septum QD0, to avoid the high background rate in the detector which would be produced by the over-bend off-energy particles if a dipolar component is present, is being studied. In the novel design, based on SC “helical-type” windings, the windings generate pure quadrupole field as a superposition of the inner field of the surrounding coil and of the outer fringe field of the neighbor one (Bettoni, Paoloni). Overall thickness ~ 8mm, leaving about 60 x of beam stay-clear. Final Focus
IP layout M.Sullivan
S. Bettoni, E. Paoloni Work in progress Example of QD0 design
Polarization Polarization of one beam is included in SuperB Either energy beam could be the polarized one. The LER would be less expensive. Long polarization times and short beam lifetimes indicate a need to inject polarized electrons in the vertical plane There are several possible IP spin rotators Solenoids look better at present Expected longitudinal polarization at the IP of about 87%(inj) x 97%(ring)=85%(effective) J. Seeman, International Review Committee Meeting, LNF, Nov.07
DA NE upgrade with “crab waist” D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, F. Bossi, B. Buonomo, A. Clozza, G. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, F. Marcellini, G. Mazzitelli, C. Milardi, F. Murtas, L. Pellegrino, M. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov (INFN/LNF) I. Koop, E. Levichev, P. Piminov, D. Shatilov, V. Smaluk (BINP) S. Bettoni (CERN, Geneva) K. Ohmi (KEK) N. Arnaud, D. Breton, P. Roudeau, A. Stocchi, A. Variola, B. F. Viaud (LAL/Orsay) M. Esposito (Rome1 University) E. Paoloni (Pisa University) P. Branchini (Roma3 University) M. Schioppa (INFN Gruppo di Cosenza) P. Valente (INFN-Roma) DA NE Upgrade Team
DA NE performances
DA NE Upgrade Parameters DA NE FINUDA DA NE Upgrade cross /2 (mrad) x (mm x mrad) x * (cm) x * (mm) Piwinski y * (cm) y * ( m) Coupling, %0.5 I bunch (mA)13 N bunch 110 z (mm) 2220 L (cm -2 s -1 ) x Larger Piwinski angle Lower vertical beta Already achieved
DA NE test expected results The upgrade of DA NE run the new collision scheme will allow for peak luminosities of cm -2 s -1 The use of “crab waist” sextupoles will add a bonus for suppression of dangerous resonances Brand new IRs layout and equipments have been designed, constructed and installed This test will have the fundamental function of validating the simulation (BBI code by K. Hirata) Luminosity vs beam current
Crab On 0.6/ Crab Off Luminosity vs tunes scan M. Zobov
Crab Waist Off Crab Waist On (K. Ohmi, BBSS Simulations) Single Bunch Luminosity Crab Waist On damping = turns damping = turns x110 bunches = cm -2 s -1 Strong-Strong Simulations
Commissioning status (1) Rings closed end November First beams beginning of December Some BPMs problems due to new RF frequency solved Maximum currents up to now 700/400 mA (e - /e + ) Found pm quads lower gradient (2%) than expected rematched optics Coupling ~ 0.4/1.1% (e - /e + ) Crab waist optics implemented, phase between sextupoles OK
Commissioning status (2) Measured -functions and dispersion in agreement with model Collisions started at 200 on 200 mA (e - /e + ), 60 bunches Measured vertical IP size: y = 8.1 m Tuning of all subsystems in progress SIDDHARTA Detector will be installed first week of February Beam currents in 24 h
New large Piwinski angle scheme in SuperB will allow for peak luminosity cm -2 s -1 well beyond the current state-of-the-art, without a significant increase in beam currents or shorter bunch lengths Use of “crab waist” sextupoles will add a bonus for suppression of dangerous resonances Expected luminosity increase due to “Crab Waist” is: a) a factor of 3, at least, for the DA NE upgrade b) about 2 orders of magnitude for the SuperB project (with respect to the existing B-Factories) The principle is being tested at DA NE Conclusions (1)
There is an international interest and participation in SuperB A CDR is being reviewed by the International Review Committee In case of positive answer a TDR will be ready by 2010 Next issues are: site, money, people Conclusions (2) Upgraded DA NE is in commissioning phase Collisions at low current started Results are expected very soon