EPS Krakow July 16-22, 2009 B-factory developments 1 e+e- Factory Developments M. Sullivan EPS 2009 Krakow, Poland July 16-22, 2009

EPS Krakow July 16-22, 2009 B-factory developments 2 Outline e+e- Factories –Introduction –Charm factories –PEP-II and BaBar –KEKB and Belle Super B-Factories –Building on the success of the B-factories –Initial designs –SuperB –DAFNE results –Super KEKB Summary and Outlook

EPS Krakow July 16-22, 2009 B-factory developments 3 High luminosity High luminosity colliders are “the other” discovery machines Developing enormous data samples enables researchers to look for rare decay-rate discrepancies which can lead to new physics These machines are an important compliment to the energy frontier machines

EPS Krakow July 16-22, 2009 B-factory developments 4 Charm Factories My primary emphasis is on B-factories but we must not forget the charm factories and phi factories BEPCII has started up and is already delivering more than 30% of their design luminosity of 1x10 33 cm -2 s -1 BINP in Novosibirsk is developing plans to make a super Tau-charm factory (1x10 35 ) DAFNE will start a new run with the KLOE detector next year (more on DAFNE)

EPS Krakow July 16-22, 2009 B-factory developments 5 PEP-II and KEKB When the PEP-II and KEKB B-factories were proposed, the highest luminosity colliding beam accelerator was CESR at Cornell with a luminosity of 8x10 32 cm -2 s -1 Achieving 3x10 33 and possibly 1x10 34 was considered quite a stretch Both machines reached 1x10 34 and KEKB has just recently reached 2x10 34

EPS Krakow July 16-22, 2009 B-factory developments 6 B-Factories  -Factories Future Colliders Linear colliders Super Factories e+e- Colliders

EPS Krakow July 16-22, 2009 B-factory developments 7 Accelerator Advances The B-factories used or pioneered: –Bunch-by-bunch feedbacks (both transverse and longitudinal) –High current stored beams –High power RF systems –Two storage rings (tried earlier) –Large number of beam bunches (>1000) –Crossing angle (KEKB)

EPS Krakow July 16-22, 2009 B-factory developments 8 BaBar and Belle The BaBar detector collected over 500 fb -1 of data Belle is still collecting and has nearly 1000 fb -1 of data (1 ab -1 ) Together the two experiments have over 10 9 BBbar events The PDG pocket book has gotten significantly thicker The precision on the unitarity triangle parameters has dramatically improved Both experiments are looking for new physics

EPS Krakow July 16-22, 2009 B-factory developments 9 Interest in a Super B-factory The success of the B-factories has generated interest in an even higher luminosity collider An increase in luminosity of almost 100 from the present B-factories starts to push the search for new physics well above the 500 GeV mass range Integration expectations are for 10 ab -1 per year

EPS Krakow July 16-22, 2009 B-factory developments 10 How to get 100 times more  y Vertical beam-beam parameter  I b Bunch current (A)  n Number of bunches  y * IP vertical beta (cm)  E Beam energy (GeV) Present day B-factories PEP-IIKEKB E(GeV) 9x3.18x3.5 I b 1x x1 n I (A) 1.7x x1.6  y * (cm)  y L (x10 34 ) 1 2 Luminosity equation Answer: Increase I b Decrease  y * Increase  y Increase n

EPS Krakow July 16-22, 2009 B-factory developments 11 Getting more Difficult to increase the beam-beam parameter much above present levels –Some beam-beam simulations say higher values are possible Number of bunches is roughly the same as present B factories –Either the rings get much larger or the RF frequency gets much higher So concentrate on increasing the I b and lowering the  y * –But… –More I b means more total current –Smaller  y * means shorter bunches

EPS Krakow July 16-22, 2009 B-factory developments 12 High-current Super B-factory Designs PEP-III(2004) SuperKEKB(2008) Energies 8x3.5 8x3.5 I b (mA)1.5x3.30.8x1.9 n I(A) 10x234.1x9.4  y * (mm) 1.8 6x3  y x0.5 Xing (mrad) to 0 Lumi(x10 34 ) Traveling focus High tune shifts w/crab cavity Very short bunch

EPS Krakow July 16-22, 2009 B-factory developments 13 A Difficult Recipe Higher currents and shorter bunches lead directly to much higher wake-field effects –HOM power and CSR Vacuum chamber impedances must be minimized –Causes bunch lengthening –Hard to do a lot better than present B-factories All components must be water-cooled –Again, difficult to do much better than present B- factories SR power levels increase with higher beam currents causing higher total beam losses –More RF power needed to restore the lost beam energy – more plug power

EPS Krakow July 16-22, 2009 B-factory developments 14 A New Idea Pantaleo Raimondi came up with a new scheme to attain high luminosity in a storage ring –Change the collision so that only a small fraction of one bunch collides with the other bunch Large crossing angle Long bunch length –Due to the large crossing angle the effective bunch length (the colliding part) is now very short so we can lower  y * by a factor of 50 –The beams must have very low emittance – like present day light sources The x size at the IP now sets the effective bunch length –In addition, by crabbing the magnetic waist of the colliding beams we greatly reduce the tune plane resonances enabling greater tune shifts and better tune plane flexibility This increases the luminosity performance by another factor of 2-3

EPS Krakow July 16-22, 2009 B-factory developments 15 More on the New Idea Back to the luminosity equation –Beam currents are about the same as present day B-factories –Number of bunches about the same –Tune shifts are about the same What is so hard? –Colliding light source emittance beams (not been done) –Keeping the coupling very low –Making it work with an HEP detector field –Developing a final focus that can deliver the very small  *s –Having acceptable backgrounds and beam lifetimes

EPS Krakow July 16-22, 2009 B-factory developments 16 How the crabbed waist works Crab sextupoles OFF: Waist line is orthogonal to the axis of the beam Crab sextupoles ON: Waist moves parallel to the axis of other beam: maximum particle density in the overlap between bunches Plots by E. Paoloni All particles in both beams collide in the minimum  y region, with a net luminosity gain

EPS Krakow July 16-22, 2009 B-factory developments 17 Typical case (KEKB, DA  NE): 1. low Piwinski angle  < 1 2.  y comparable with  z Crab Waist On: 1. large Piwinski angle  >> 1 2.  y comparable with  x /  Much higher luminosity! D.Shatilov’s (BINP), ICFA08 Workshop x-y resonance suppression

EPS Krakow July 16-22, 2009 B-factory developments 18 LER/HERUnitJune 2008Jan. 2009March 2009LNF site E+/E-GeV4/7 Lcm -2 s -1 1x10 36 I + /I - Amp1.85 / / / /2.70 N part x /5.556/64.37/ /4.53 N bun I bunch mA  mrad2530 x*x* mm35/20 y*y* mm0.22 / /0.37 xx nm2.8/1.6 yy pm7/4 xx mm 9.9/5.7 yy nm39/3938/38 zz mm5/5 xx X tune shift0.007/ / / yy Y tune shift0.14 / / / /0.095 RF stationsLER/HER5/6 5/86/9 RF wall plug powerMW Circumferencem1800* 1400 # SuperB Parameters *Antisymmetric Spin Rotators add 300 m, # Symmetric Spin Rotators included

EPS Krakow July 16-22, 2009 B-factory developments 19 Other Features Beam lifetime is low primarily due to the high luminosity (~10 min) –Must use continuous injection for both beams –Techniques pioneered by PEP-II and KEKB We can have a polarized beam by injecting polarized electrons –Unique opportunity –Just have to avoid depolarizing resonances – depolarizing times must be at least min Recycle the PEP-II hardware –Magnets, vacuum chambers, RF systems, feedback systems

EPS Krakow July 16-22, 2009 B-factory developments 20 The IR design The interaction region design has to accommodate the machine needs as well as the detector requirements –Final focus elements as close to the IP as possible –As small a detector beam pipe as backgrounds allow –As thin as possible detector beam pipe –Adequate beam-stay-clear for the machine Low emittance beams helps here –Synchrotron radiation backgrounds under control –Adequate solid angle acceptance for the detector

EPS Krakow July 16-22, 2009 B-factory developments 21 Final focus magnets Up to now, factories have typically developed interaction regions with at least one shared quadrupole However, with the large crossing angle of the SuperB design this means at least one beam is far off axis in a shared magnet This magnet therefore strongly bends the off- axis beam which produces powerful SR fans and even emittance growth To avoid this, the SuperB design has developed a twin final focus doublet for both beams

EPS Krakow July 16-22, 2009 B-factory developments 22 R&D on SC Quadrupoles at the IP Total field in black Coils array Most recent design with BSC envelopes E. Paoloni (Pisa), S. Bettoni (CERN)

EPS Krakow July 16-22, 2009 B-factory developments 23 The Present Design

EPS Krakow July 16-22, 2009 B-factory developments 24 Inside the detector

EPS Krakow July 16-22, 2009 B-factory developments 25 Latest IR Design Crossing angle of +/- 30 mrads Cryostat has a complete warm bore –Both QD0 and QF1 are super-conducting PM in front of QD0 for the LER only –LER has the lowest beta Y* Soft upstream bend magnets –Further reduces SR power in IP area Increased BSC to 30 sigmas in X and 140 sigmas in Y (10 sigma fully coupled) We are using the highest luminosity design parameters –Lowest beta* values and highest emittances Do NOT want to design out upgrades

EPS Krakow July 16-22, 2009 B-factory developments 26 Parameters used for the IR design Parameter HER LER Energy (GeV) 7 4 Current (A) Beta X (mm) Beta Y (mm) Emittance X (nm-rad) Emittance Y (pm-rad) Sigma X (  m) Sigma Y (nm) Crossing angle (mrad)+/- 30

EPS Krakow July 16-22, 2009 B-factory developments 27 SR backgrounds SR backgrounds influence the IR design No photons strike the physics window –We trace the beam out to 20  X and 45  Y –The physics window is defined as +/-4 cm for a 1 cm radius beam pipe Photons from particles at high beam sigmas presently strike within 5 cm downstream of the IP –1 cm downstream of the Be physics window Unlike PEP-II, the SuperB design is sensitive to the transverse beam tail distribution

EPS Krakow July 16-22, 2009 B-factory developments e e7 5.7e5 9.9e6 6.9e5 Photons/beam bunch HER LER

EPS Krakow July 16-22, 2009 B-factory developments 29 SR backscatter estimates First order look at backscattering –Use a small program to calculate solid angle fractions from a source of photons to the IP beam pipe –Estimate backscatter rate from a surface. Use 3% of the incident rate and assume that it is isotropic –Then calculate solid angle fraction to the IP –This is a decent first order approximation and it is conservative

EPS Krakow July 16-22, 2009 B-factory developments e5 9.9e6 6.9e5 Backscattered photons/beam bunch inc. on Be >10 keV HER LER

EPS Krakow July 16-22, 2009 B-factory developments 31 SuperB Site Choices C ~ 2.1 km SPARX-I SPARX-II SuperB LINAC Det. Hall SuperB Rings Frascati National Laboratories Existing Infrastructure University of Tor Vergata Campus Green Field Site C ~ 1.4 km Det. Hall Injector

EPS Krakow July 16-22, 2009 B-factory developments 32 DAFNE test bed About two years ago the DAFNE team decided to upgrade the accelerator to test the crab waist scheme This past year they have been gradually getting the machine back up and running and have successfully demonstrated the effectiveness of the large crossing angle (large piwinski angle) with the crabbed magnetic waist

EPS Krakow July 16-22, 2009 B-factory developments 33 DA  NE (KLOE run) DA  NE Upgrade I bunch (mA)13 N bunch 110  y * (cm)  x * (cm)  y * (  m) 5.4 low curr3.1  x * (  m)  z (mm) 2520 Horizontal tune shift Vertical tune shift  cross (mrad) (half)  Piwinski L (cm -2 s -1 )1.5x10 32 >5x10 32 DA  NE (KLOE run) DA  NE Upgrade BEAM AND NEW PARAMETERS 3 times more luminosity obtained just with 3 times smaller vertical beam

EPS Krakow July 16-22, 2009 B-factory developments 34 New Siddharta IR at DAFNE

EPS Krakow July 16-22, 2009 B-factory developments 35 Luminosity [10 28 cm -2 s -1 ]  y=18mm, Pw_angle=0.6  y=9mm, Pw_angle=1.9  y=25mm, Pw_angle=0.3 LPA alone gives more luminosity Data averaged on a full day

EPS Krakow July 16-22, 2009 B-factory developments 36 Present Performance with upgrade before Peak Luminosity (10 32 ) e- current (A) e+ current (A) Number of bunches Peak Hourly rate pb Peak Daily rate pb The daily rate is with long coasting (Long coasting needed for Siddharta, not for Kloe or Finuda) Red are the Kloe records before the upgrade

EPS Krakow July 16-22, 2009 B-factory developments 37 The results are even more striking since they reduced the Dafne wiggler field (less damping needed since the beam-beam is smaller) in order to save on running costs: - 6 MW Wall plug power during Kloe data taking - 4 MW now Performance is still limited because of “standard problems”: - e-cloud - Ion trapping - RF stability They plan to work more on these issues and hope to gain more in Luminosity at a given current and at peak currents

EPS Krakow July 16-22, 2009 B-factory developments 38 Super KEKB Until this year the super KEKB design used high bunch currents and short bunch lengths with the crab cavity and high tune shifts to get the high luminosity They had found that the bunch length of the LER could not be shorter than 5 mm due to CSR effects which led them to consider a traveling focus scheme using sextupoles next to crab cavities near the IR This leads to a magnetic focus that is at a different z location as a function of z position in the bunch X  x =   y =  SX1SX2 SX1SX2 Crab  x =  /2  y =  IP  x =  /2

EPS Krakow July 16-22, 2009 B-factory developments 39 Super KEKB now an upgrade Recently KEKB decided to adopt the SuperB collision scheme and beam parameters, in order to overcome the high-beam currents and power issues The new scheme, called “nanobeams” or “Italian” will reach 8x10 35 cm -2 s -1 They will need to rebuild the two rings (most of the magnets and all of the beam pipe will be replaced, new damping ring, etc...). The “crab waist” sextupoles are an option Some R&D money has been provided for this year A government decision for the upgrade is expected before the end of this year If approved, operation is expected to start by the end of 2013, assuming KEKB turns off in March 2010

EPS Krakow July 16-22, 2009 B-factory developments 40 SuperB and Super-KEKB ParameterUnitsSuperB Super-KEKB Old scheme Super-KEKB Italian scheme EnergyGeV4x73.5x8 Luminosity10 36 /cm 2 /s to Beam currentsA2.0x2.09.4x4.13.8x2.2 N bunches Ey* (L/H)pm7/4240/9034/11 Ex* (L/H)nm2.8/1.624/182.8/2 By* (L/H)mm0.21/0.373 Bx* (L/H)cm3.5/ /2.5 Sz (L/H)mm5/55/35/5 Crossing angle (full)mrad6030 to 060 RF power (AC line)MW2690>50 Tune shifts (L/H)0.125/ / /0.081

EPS Krakow July 16-22, 2009 B-factory developments 41 Summary Super B-factory designs are firming up The designs are converging to the “Italian” scheme of low emittance beams with a large crossing angle and a longer (more typical) bunch length A super B-factory with 100 times the luminosity of present day B-factories is becoming more and more feasible Both design efforts hope to get government approval in the near future

EPS Krakow July 16-22, 2009 B-factory developments 42 Outlook A very high luminosity B-factory is a strong compliment to the energy frontier (LHC and ILC) The two present B-factories together have supported over 1000 physicists and have produced over 500 Phds There are hundreds of new entries in the particle data book from the data generated by the B-factories The surprising fact is that the B-factories have NOT found any new physics The Standard Model is (amazingly) still intact

EPS Krakow July 16-22, 2009 B-factory developments 43 Conclusion A super B-factory will push the Standard Model limits into regions where SUSY models and Higgs models start making predictions The LHC alone may have a hard time digging out all of the new physics A complimentary super B-factory could be a great help in finding any new physics I think that with the combination of the LHC, a super B-factory and the ILC, HEP has a strong future