Fast luminosity measurements and MDI questions for super B factories A_RD_8_2012 Philip Bambade LAL: P.B., F. Blampuy (grad. student), C. Rimbault (Acc. Dept.), F. Bogard & S. Wallon (mechanical eng.) KEK: S. Uehara, Y. Funakoshi, M. Iwasaki Joint TYL-FKPPL workshop, Clermont-Ferrand May 2012

Y. Ohnishi (KEK, joint bkgd w.s., Feb. 2012

Parameters ATF2 ILCCLIC Beam Energy [GeV] L* [m]  x/y [m.rad] / / / IP  x/y [mm] 4 / / / 0.07 IP  ’ [rad]  E [%] ~ 0.1 ~ 0.3 Chromaticity ~  / L* ~ 10 4 ~ Number of bunches1-3 (goal 1)~ Number of bunches3-30 (goal 2)~ Bunch population IP  y [nm] ATF2 = scaled ILC & CLIC final focus Super-KEKB / Super-B /

Luminosity operational mode & backgrounds / MDI design dominated by several beam loss processes ee  eeee process (pair bkdg in VD) M. Boscolo (LNF, SuperB meeting, March 2012 Y. Funakoshi (KEK, joint bkgd w.s., Feb. 2012

Aim of A_RD_8_2012 is to collaborate & exchange on: 1) simulating & comparing several background / particle loss processes 2) fast luminosity monitoring methods

Radiative Bhabha (“Compton”) process can be used for luminosity monitoring Represents major background source via particle loss after IP  ~ 250 mbarn (E  > 1% E beam )

F. Blampuy (LAL)

Different EPA factorization methods

Y. Funakoshi (KEK, joint bkgd w.s., Feb Macroscopic quantum effect… issue for luminosity monitoring ?

Where are the signals? R-side L-side Outside HER LER  from electron Recoil  electron Recoil  positron  from positron 12

Specifications and rates Ground motion analysis and experience from Belle & PEP-II Relative accuracy 10 6 at kHz L ~ cm -2 s -1  ~ 250 mbarn (E  > 1% Ebeam )  expected total rate ~ / s Should also work for lower initial luminosities: range

Possible locations Possible problems: Material quantity of the beam chamber in r.l. Undesirable sensitivity to angle and position/size of the beams at IP , e + -side , e - -side Deflected e- Deflected e+ Downstream magnets from Masuzawa-san R-sideL-side Outside 14 S. Uehara and Y Funakoshi (KEK)

F. Blampuy (LAL) 2 candidate locations in SuperB LER 5 cm Estimated counting rate in 5  5 mm 2 diamond sensor placed 3.5 cm from beam ~ / s Mechanical adjustment and / or structure with variable size strips can provide some dynamic range

Hyojung Hyun (LAL, KNU)

Hyojung Hyun (LAL, KNU) 1 st LAL, April 2012 Frédéric Bogard (LAL) ABCD Project ATF2 Beam halo and Compton electron Diamond sensor project

LER Loss Position & Rate 0.1mA/s -> 6.2GHz 18 Y. Funakoshi (KEK)

Loss point の座標（ transverse ） 4m < s < 16m (s は IP からの距離 ) 19 Y. Funakoshi (KEK)

Expected ZDLM rate (Uehara) Funakoshi-san’s coefficient The rate should be proportional to luminosity luminosity --- ~ 1GHz -Effective detector length --- ~ 0.1m -Efficiency % (angular coverage and shower loss) Expected Rate mA/s  10 MHz LER 4 m point (upstream BLC1LP) ~ 35 9 m point (downstream BLC1LP) ~ m point (downstream QKBLP) ~ 35 QKBLP- skew -- Efficiency may drop (spread to non- horizontal direction) 0.1mA/s -> 6.2GHz 20

Readout Methods 1. Counting rate -- proportional to Luminosity Rate < 1% of Collision rate to avoid overlaps, (< 2.5MHz) Collision rate (2-bucket spacing) 250MHz ~ MHz --- 1% stat. accuracy in 100Hz readout ~ kHz --- 3% stat. accuracy in 100Hz readout Tune depends on Luminosity Charge amp (Makes slow change) → V/F conversion (1MHz max) for SuperKEKB Analog input (with pulse overlaps) is also OK in this scheme? 21

Check for any Touschek or beam gas scattering losses in candidate areas for fast luminosity monitoring

Work plan (KEK, LAL)  SuperKEKB/Belle II could be necessary, possible and should be prepared. -Choices for hardware and location undergoing. -Aiming full-duty factor in the high rate -Wide L range – /cm2/s -Simulation study for dithering (active feedback) is performed  Fast luminosity monitor(s) being investigated for SuperB -Further checks / comparisons of cross-section and generator -MAD tracking in lattice to define best locations -GEANT4 for acceptance and detector layout optimization -Requirement on beam pipe shape from HOM (for photon detection) -Vacuum chamber design and magnet shapes, synchrotron rad. -Background from non-L scaling beam losses: Touschek, beam gas -Diamond sensor implementation (for ATF2 beam halo) and characterization -Readout (for ATF2, Parisroc2 front-end electronics OK  also for superB ?) A bit more advanced… Experience from KEKB Starting effort… Some synergies with ATF2 / LC R&D Connected to LNF, BINP and JAI teams

F. Blampuy, student f C. Rimbault LAL/IN2P3 CR2 Interesting collaboration prospects between LAL and KEK and between SuperB / SuperKEKB !

Additional slides

HER Loss Position & Rate 0.1mA/s -> 6.2GHz 26 Y. Funakoshi (KEK)

Loss point の座標（ transverse ） 4m < s < 16m 27 Y. Funakoshi (KEK)

Readout Methods 2. Bunch-by-Bunch Luminosity Readout --- Trying a method to use pipeline TDC AMT3/COPPER (Belle standard) Time step 738ps No dead time, if word count is not too large. Under test bench Thank to Higuchi-san Test Condition: 2MHz ~ 1 %/bunch-collision for 2000-bunch operation ~20 hit/rev, ~ 1000 cps/bunch Data amount: ~ O(10) MB/sec in raw data --- transfer only count-data via network (after histograming) : only ~100KB every second 28

Near term planning 1.R&D grant from P2IO LABEX covering PhD grant from CSC-FCPPL (S. Liu, 3 years starting ) Collaboration with KNU and post-doc application (H. Hyun, H. Park) 2.Design / lab test at LAL : mechanics, electronics (PARISROC2) and more detailed simulations. Experience from FCAL coll. at DESY-Zeuthen. 3.New vacuum chamber fabrication and quadrupole installation at KEK 4.Aim to test 1 st prototype in ATF2 beam  end 2012 / early 2013 tentative schedule