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Sp Spin in tr treatme atment nt at t th the IL ILC: ove verview, rview, sta tatus, tus, needs ds and d ope pen n qu quest estions ions G. Moortgat-Pick (Uni Hamburg/DESY) 1 World ld-wide wide Even ent On June 12 th

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Sp Spin in tr treatme atment nt at t th the IL ILC: ove verview, rview, sta tatus, tus, needs ds and d ope pen n qu quest estions ions

  • G. Moortgat-Pick

(Uni Hamburg/DESY)

1

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World ld-wide wide Even ent

  • On June 12th,2013, ILC TDR was published in Worldwide Event.

2

  • End of major phase in ILC development – now what?

Eucard@Mainz 2/2014 Gudrid Moortgat-Pick

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3 LHC timeline

Eucard@Mainz 2/2014 Gudrid Moortgat-Pick

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Japanese Site for ILC

  • LCC Directorate official

site visit Oct. 2013.

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Brock ck Sn Snowma wmass ss Su Summ mmar ary

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Brock ck Sn Snowma wmass ss Su Summ mmar ary

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SLIDE 7

The L e LC physics ics off ffer er a and ch chal alle lenges es

  • Staged energy approach:

– √s~240 GeV, `Higgs frontier‘ – √s~350 GeV, `Top threshold‘ – √s~500 GeV, `Top Yukawa‘ – (√s=91 GeV, `EW Precision frontier‘ ) – √s~1000 GeV, `Higgs potential‘

  • Polarized beams and threshold scans:

– impact on ‘quality’ (and quantity) – Something ‘new’ comp. to LHC analyses

  • Highest precision: precise spin treatment required

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SLIDE 8

IL ILC Mac achin ine e Lay ay-ou

  • ut
  • About 30 km in first stage √s=500 GeV, crossing angle 2x7 mrad
  • High luminosity: 2x1034cm-2s-1
  • Running time: 75% per year
  • Beams: 2x1010/bunch, 1312 bunch/pulse, 5 Hz rep. rate for

√s=350 and 500 GeV

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IL ILC Ma Mach chine ine Ov Overvie erview

Damping Rings Polarised electron source Polarised positron source Ring to Main Linac (RTML) (inc. bunch compressors) e- Main Linac Beam Delivery System (BDS) & physics detectors e+ Main Linac

Beam dump not to scale

9

σx / σy - 474 nm / 6 nm Luminosity - 2×1034 cm-2s-1 Polarisation (e-/e+) - 80% / 30%

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ILC LC Pa Paramet rameters ers

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Sc Scope pe req equirements: uirements: ICFA A LC LC Pa Parameter ameter

  • ‘Scope Document no.1’ (2003) and ‘no.2’ (2006): baseline

– Full luminosity of 2x1034cm-2s-1 – Beam energy stability and precision below tenth of percent level – Machine interface must allow measurements of beam energy and differential luminosity spectrum with similar accuracy – Electron beams with polarization of at least 80% within whole energy range

  • Options:

– e+ polarization ~50% in whole energy range – GigaZ= high lumi run at the Z-pole/WW threshold: energy stability and calibration accuracy below tenth of percent level

Exploitation of polarization needs particular treatment

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El Elec ectron tron polarization larization

  • Similar as SLC e- source: but now for long trains and high

RF power

– DC gun: e- with 200keV – Laser: λ=790nm , based on TiSapph, – cw. Nd:Yag laser provides power

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Po Posit itron ron source ce

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  • Choice: e+ via radiation from a helical undulator (because of

higher yield, less rad. level, better DR accept., less target stress )

See Andriy’s and Friedrichs talks

(Target processes: Olufemi Adeyemi)

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Po Pola lariza rization:T tion:Tec echnic hnical al fa fact cts s I

  • P(e-) ~ 80-90%
  • P(e+) (always yield ≥1.5 imposed):

√s=240 GeV: 120 GeV e- drive beam

– Undulator with 231 m (K=0.92, λ=11.5 mm), collimator r=3.5 mm – P(e+)~ 40%

√s=350GeV: 175 GeV e- drive beam

– Collimator with r=1.2 mm – P(e+)~ 56%

√s=500GeV: 250 GeV e- drive beam

– Undulator with 144 m, collimator r=0.7mm – P(e+)~59%

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Eb=175 GeV Andriy Ushakov,

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Techn chnica ical l fa fact cts s II

  • P(e+) (always yield ≥1.5 imposed):

√s=1 TeV: 500 GeV e- drive beam

– Undulator with 176 m (K=2.5), collimator r=0.9mm – P(e+)~54%

  • Measurent of polarization:

– Compton polarimetry (up- and down-stream): δP/P=0.25% – Via WW-process (lumi-weighted!): δP/P(e-)~0.1%, δP/P(e+)~0.2-0.3%

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See Annika’s talk

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Spin in sensit itive ive comp mpone nents ts

  • Spin rotator before / after damping rings
  • (Fast) helicity flipping of the e+ required:

– Apply kicker at the damping system

  • Polarization measurement (polarimetry, lumi-weigthed)
  • QED processes at beam-beam interaction

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see Sabine’s talk see Tony’s talk see Moritz and Annika’s talks

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Bea eam-bea eam: m: strong

  • ng fi

fiel elds in in IR IR

Eucard@Mainz 2/2014 Gudrid Moortgat-Pick 17

Tony Hartin

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Sp Spin in Rotat ator

  • r Sy

Syst stem em

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Valentyn Kovalenko

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Posit itron ron Lin inac ac to Rin ing Bea eaml mlin ine e

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La Latti ttice ce Spin pin Fli Flippe pper

Eucard@Mainz 2/2014 Gudrid Moortgat-Pick 20

Larisa Malysheva

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BMAD: D: Sp Spin in Trac acki king g in in PL PLTR (u

(up p to to spi pin fli lipp pper) er)

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Sp Spin in trac acki king: g: spin in fl flip ipper er

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Post t DR DR Sp Spin in Rotato tor

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X-Y Y Coupling upling

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Emm mma Ro a Rotat ator:

  • r: phas

ase e spac ace e unchanged

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Sp Spin in rot

  • tator

ator an and em emittance ittance preservati eservation

  • n

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  • Depolarization <0.1%
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Em Emitt ittance ance preservation eservation

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Re Resona sonant nt De Depolariz polarization ation

  • Unpolarized configuration highly desirable

– Get systematics under control, etc.

  • Helical undulator radiation: always polarized

– Question: if only medium/low polarization available possible to destroy polarization if no spin rotators are used before the DR? – No, since no complete decoherence! See study of Barber/ Malysheva

  • Proposal: use RF kickers to get resonant depolarization

– Study done by Valentyn Kovalenko within this BMBF project together with M. Vogt, A. Wolski – Simple spin model used so far, but looks promising

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Re Resonant sonant De Depolarization polarization

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Valentyn Kovalenko

Use

  • scillating

magnetic field (kicker) Kicker field is ┴ beam axis

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Anal alyti tica cal l ap approa

  • ach

ch

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Us Used ed (simple) imple) spin pin mo model del

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Pr Prin inci cipal pal fe featur ature

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Applica pplication tion to Re Real al la lattice ttice

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Compar mparison ison co codes es SA SAMM+SPRINT M+SPRINT

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Comp mparison arison wit ith an analyti alytica cal l ap appr proach

  • ach

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Influence fluence of bea eam m geo eometry metry

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First results indicate:

  • Feasibility of

resonant depolarization technique at ILC

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Op Open n is issues ues

Not a complete list ( just as proposals for ‘To-do-list):

– Inclusion of effects of synchrotron radiation and radiation damping – Test of different spin models (?) – Inclusion of accurate spin tracking in damping ring – Linking different codes for different sections to provide full cradle-to-grave tracking code – Inclusion of non-Gaussian beams in beam-beam studies – ….

Eucard@Mainz 2/2014 Gudrid Moortgat-Pick 37

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Conclusions clusions

  • Beam polarization gives ‘added-value’ to ILC

– Provides ‘new’ analysis tools comp. with LHC and highest precision – Requires complete spin control

  • Positron polarization

– Enhances eff. Lumi, provides higher prec. – full energy range: √s=92,…,1000 GeV ! – Fast helicity reversal is required

  • Spin tracking from source to downstream polarimeter

– Spin rotator system – RF kicker for ‘unpolarized’ option – Depolarization and strong field effects in IP region

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