INJECTION SYSTEM UPDATE R.Boni, S.Guiducci, M.Preger, P. Raimondi, LNF J.Seeman, SLAC O. Dadoun, F. Poirier, A. Variola, IN2P3 XI SuperB General Meeting – LNF – Dec. 2009 With respect to the previous solutions, the IN2P3 group proposes a scheme with e+ production at lower energy (0.6 vs 6 GeV) (see Variola talk). The positron surplus is less, but the linac is more compact and less expensive. Otherwise, if the positron yield of the above solution will be considered not enough, an injection scheme with a recirculation line can provide a number of positrons per shot, amply sufficient for topping-up the HER. In both cases, one damping ring can be used for both e- and e+ This presentation follows those of : Isola d’Elba …. June 2008 LNF Mini-Mac …. July 2008 Orsay Workshop …. Febr. 2009 LNF Mini Mac …. Apr. 2009 Perugia workshop ... June 2008 SuperB

# # # # INJECTION SCHEME with e-/e+ production at Low Energy 1 Damping Ring for both e- and e+ # Electron-positron conversion at lower energy (*) # Reduced tunnel length, because low and high energy linacs share the same gallery section # HER and LER rings filled every 40 msec (25 Hz) (*) subject to the IN2P3 simulations SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

t1 e+ injection in HER and …… low charge e- in DR INJECTION SCHEME with e-/e+ production at low energy INJECTION PHASES t1 e+ injection in HER and …… low charge e- in DR t t2 = t1 + 20 msec e- injection in LER and …. positrons in DR t > 4 GeV 6 GeV 3 GeV SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

Rings injection rate: 40 msec (i.e. @ 25 Hz) INJECTION SCHEME with e-/e+ production at low energy TIMING t1 t2 t1 t2 20 msec 20 msec e- prod. e+ prod. e- prod. e+ prod. e+ Inj. e- Inj. e+ Inj. e- Inj. 40 msec 40 msec Rings injection rate: 40 msec (i.e. @ 25 Hz) e- DR storage time = 20 msec e+ DR storage time = 20 msec SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

Layout still schematic but to scale INJECTION SCHEME with e-/e+ production at low energy D.R. & T.L. outline ≈ 13 m ≈ 5 m 18 m. Layout still schematic but to scale SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

# # # A B INJECTION Scheme with Conversion at 6 GeV Injection process in 3 phases, to avoid simultaneous acceleration of high-charge e- bunches and damped e+ bunches in the linac B. # HER and LER rings filled every 60 msec (16.66 Hz) # 1 Damping Ring for both e- and e+ DR SLAC polarized gun A > 7 GeV e+ SHB 1 GeV > 5 GeV 0.2 GeV 0.8 GeV B PS > 4 GeV e- Schematic Layout SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

RECIRCULATED INJECTION SCHEME Injection phases t1 e+ injection in HER and …… low charge e- in DR DR e+ to HER P P DC DC P P t2 = t1 + 20 msec e- injection in LER DR P P DC e- DC to LER P P t3 = t1 + 40 msec e+ production DC DR PS DC high charge e- bunches SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

Rings injection rate: 60 msec (i.e. @ 16.666 Hz) RECIRCULATED INJECTION SCHEME TIMING t1 t2 t3 t1 t2 t3 20 msec e- prod. e+ prod. e- prod. e+ prod. e+ Inj. e- Inj. e+ Inj. e- Inj. 60 msec 60 msec Rings injection rate: 60 msec (i.e. @ 16.666 Hz) e- DR storage time = 20 msec e+ DR storage time = 20 msec SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

RECIRCULATED INJECTION SCHEME D.R. & T.L. outline SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

DR & TL phases t2 = t1 + 20 ms t1 t3 = t1 + 40 ms e- injection RECIRCULATED INJECTION SCHEME DR & TL phases k1 ≈ 60 ÷ 70 ns t e+ e- DR k2 t2 = t1 + 20 ms t1 k1 DR k3 k4 k3 SR e+ t e- e+ e- PM PM PM PM e- injection e- production and e+ injection t3 = t1 + 40 ms DR k2 k4 e+ high charge e- e+ production SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

Parameter list 1 GeV Damping Ring … for details, see Perugia workshop Energy (GeV) 1.0 Circumference (m) 51.1 Horizontal betatron tune 7.40 Vertical betatron tune 2.72 Momentum compaction 0.0057 Horizontal phase advance per cell (deg) 270 Vertical phase advance per cell (deg) 90 Maximum horizontal beta (m) 7.9 Maximum vertical beta (m) 7.3 Maximum dispersion (m) 0.77 Uncorrected horizontal chromaticity -11.5 Uncorrected vertical chromaticity -8.7 Equilibrium horizontal emittance (nm) 23 Horizontal betatron damping time (ms) 7.26 Vertical betatron damping time (ms) 7.36 Synchrotron damping time (ms) 3.70 Equilibrium energy spread (%) 0.062 RF frequency (MHz) 476 Harmonic number 81 RF voltage (MV) 0.5 Bunch length (low current, cm) 0.48 K S SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

SLAC Polarized Gun courtesy A. Brachmann Parameter SLC gun Electron charge per bunch 16 nC Bunches per pulse 2 Pulse rep rate 120 Hz Cathode area 3 cm2 Cathode bias -120 kV Bunch length 2 ns Gun to SHB1 drift 150 cm en,rms,gun (fm EGUN) 15•10-6 m SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

Standard solution, adopted in other labs (SLAC, IHEP,….) Bunching System The Bunching System performs bunch length compression from 1 nsec to 10 psec. 2856 MHz 238 MHz 476 MHz 10 ps 1 ns Standard solution, adopted in other labs (SLAC, IHEP,….) 2856 MHz 476 MHz 238 MHz G SHB SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

RF System For the moment, …… it is based on the use of the S-band, room temperature, technology. Klystron parameters Frequency 2856 MHz Peak power 60 MW RF pulse length 4 μsec Cathode voltage 350÷370 kV Beam current 400÷420 A HV pulse width 6 μsec FWHM Rep. rate 50 pps Accelerating Section parameters Frequency 2.856 GHz Type TW, CG Structure Disk-loaded, 3mt length Mode of operation 2π/3 Number of cells 86 (with couplers) Attenuation constant 0.57 nepers Normalized group velocity 0.0202 to 0.0065 (Vg/C) Shunt impedance 53 to 60 MΩ/m Filling time 0.85 μsec R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

RF System shopping list > 7 GeV e+ > 4 GeV e- SHB 476 MHz 238 MHz G DR PC 0.6 ÷ 1 GeV 1 GeV 6 GeV 2856 MHz 476 MHz 5 kly’s 6 kly’s 30 kly’s L ≈ 350 m. 476 MHz 2856 MHz 476 MHz 238 MHz DR PC G SHB 1 GeV 1 GeV 6 GeV 6 kly’s 5 kly’s 30 kly’s L ≈ 450 m. N. of S.band acc. sections: 124. In addition: 1 bunching cavity @ 238 MHz 1 bunching cavity @ 476 MHz 1 D.R. cavity @ 476 MHz In both cases, 42 S-band klystron stations are needed. In addition: 2 tetrodes or IOT amplifiers for the buncher 1 476 MHz klystron for the DR R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

After being successfully introduced in the FEL Spring8, the RF System option …. The option to adopt, perhaps for the high energy section, a C-band RF system, however, is still open. After being successfully introduced in the FEL Spring8, the C-band RF systems are also generating interest in European laboratories. A C-band (5712 MHz) RF system is under project for the LNF SPARC photoinjector…. The PSI Lab. (CH) is considering to use the C-band technology for its X-FEL. The main advantage of the C-band is the reduction of the linac length (≈ 30%). The C-band RF station for SPARC will employ two, 1.5m., CI, accelerating sections designed and manufactured by LNF in collaboration with local firms. The new system is expected to provide an acc. gradient > 35 MV/m. Prototyping is in progress. A 50 cm model will be brazed, vacuum and power tested by the Spring 2010  14 cm iris dia. = 14 mm courtesy D. Alesini, L. Ficcadenti, F. Marcellini, V. Spizzo, LNF R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

Linac Linac PC PS and By-pass l d Pulsed Focusing Coil Off-axis Linac section l d Linac Linac Pulsed dipoles DC dipoles PC Low charge damped electron bunches are bent by pulsed dipoles l-d and travel through the PS-hole, 2) High charge electron bunches are bent reversely and hit the PS target Generated positron bunches follow along a straigth trajectory. R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

7 x 1010 electrons in 1 nsec q ≈ 11 nC I ≈ 11 A SLAC polarized Estimate of positron charge for topping-up low energy conversion injector recirculated linac with 6 GeV conv. Injection rate 40 msec 60 msec Filling time (5 bunches/shot) 10 sec 15 sec Loss of peak luminosity L/Lp 0.967 0.95 Loss of bunch current i/io = (L/Lp)1/2 0.983 0.975 Positron/bunch at linac output (1-i/io)•nb [nb = 5.5•1010] 0.93•109 (0.15 nC) 1.37•109 (0.22 nC) Positron lost per second per ring 1.16•1011 1.71•1011 7 x 1010 electrons in 1 nsec q ≈ 11 nC I ≈ 11 A SLAC polarized electron source SuperB R.Boni, XI SuperB General Meeting – LNF – Dec. 2009

Interesting proposal of IN2P3 group: SUMMARY Interesting proposal of IN2P3 group: “ … long and tapered PC matching section allows to collect, with good efficiency, enough positrons for HER topping-up, at rather low (0.6÷1 GeV) energy conversion….” An alternative solution can be adopted if the conversion at low energy does not guarantee sufficient margin of positron current. This solution would be more expensive (because of the longer gallery). In this regard, the C-band option deserves great consideration. Use of one Damping Ring for both particle types reduces costs R.Boni, XI SuperB General Meeting – LNF – Dec. 2009