Parameter Choice for International Linear Collider (ILC) *

Transcription

1 005 ALCPG & ILC Workshops-Snowmass, U.S.A. Paramtr Choic for Intrnational Linar Collir (ILC) * J. Gao 1 Institut of igh Enrg Phsics, Chins Acam of Scincs, ijing In this papr a gnral procu to trmin linar collir paramtrs is givn. As an ampl, a paramtr list is propos for ILC with vr low unch charg. Th main aim of this papr is to monstrat th am paramtr lations with th constraints from th intraction point an amping ring. It is suggst that th nrg of th amping ring shoul 7 GV insta of 5 GV for a 17km amping ring. K wors linar collir, ILC, paramtr, amping ring 1. ITROUCTIO In August 004, it has n announc in ijing th Intrnational Tchnolog Rcommnation Panl (ITRP) that th nt gnration +- linar collir will as on supr-conucting acclrator tchnolog [1], nam Intrnational Linar Collir (ILC). To mak ILC succssful, a asonal ILC sign is vr important. In this papr, w will provi a gnral procu to mak a linar collir paramtr choic taking into account of primntal ackgroun noiss at th intraction point (IP), tchnical fasiilit, oprational stailit, tc., oth in th main linac an th amping rings. In sction, w iscuss th am paramtr lat to th constraints from IP an amping ring. In sction, an ILC paramtr list with vr low unch charg is propos.. EAM PARAMETER RELATIOS Th luminosit of two Gaussian -on colliing ams is givn : fp L (1) 4π wh f f is th ptition fqunc of th unch train, is th numr of unchs in th train, is th numr of particls pr unch, ε β, εβ, β, an ε, a th valus of th ta functions at th IP an th mittancs, spctivl, an is th pinch nhancmnt factors which a functions of th so-call isruption paramtrs, of a unch. In th following w will pss th luminosit an colliing am paramtrs as th function of constrains from IP (flat am cas). * Support SFC. 1) gaoj@ihp.ac.cn ILCAW0806 1

2 p n γ γγ L f () π r.6δ α n γ γ γ () a n γ 41.5δ α (4) n γ γ z 4.6δ α (5) R 16πα a 4 (6) n γ γ γ β.5πγ (7) δ nγ γγ β /0.75 (8) z γε π (9).4δ α γγ γε 0.75nr (10) 74δ α γ 4 π r (11) 5.δ α γγ n θ γ θ αγ (1) f p Ln γ γγ (1) P π W r n L 10.4 (14) cm γ δ α wh m is th classical lctron raius, α is th fin structu constant, γ is th ratio of th colliing particl nrg to its st nrg, γγ m is th γγ to ron total cross sction, δ is th amstrahlung nrg spa, n γ is th avrag photon numr mitt pr incint particl, is numr ron ILCAW0806

3 prouc pr crossing, an is aout 1.5 with 9 which is us latr in this papr. In aition to constraints at IP, in amping ring, th spac charg ffct shoul liminat right from th am paramtr choic (s Eq. 15). Th tolral spac charg tun shift pss in Eq. 16 can trmin from Eqs. 17 an 18 [] γ (15) z, δ α γγ π ξsc, nγ L r L ξ (16) ( π ) ( ε ε ) β γ / 1/ n, n, z, τ ξ 1 τ, ( ) p πξ πξ R( ξ ) p τ τ st, ( ξ ) (17) (18) wh L, γ,,, z, an β a th circumfnc, normaliz nrg, unch lngth, an th particl s normaliz vlocit of an in a amping ring, spctivl, τ is th am liftim u to nonlinar spac charg ffct, τ st, is th am sto tim, an finall, R( ξ ) is th ratio of th jct particl numr to that of injct in a amping ring.. VERY LOW CARGE CASE Givn th sign am nrg of 50 GV, th luminosit aftr pinch ffct, shown in Tal 1, on gts th am paramtrs shown in Tal. L cm s, an th constraints Tal 1. Constrain paramtrs from IP. δ n γ Tal. am paramtrs at IP. ILCAW0806

4 As for amping ring, w assum that th amping ring s paramtr is as shown in Tal, on gt th spac charg tun shift to 0.05 which is saf from th nonlinar spac charg ffct. Th main iffnc from th actual amping sign is that th amping ring s nrg is 7 GV insta of 5 GV. Th main linac s paramtrs is givn in Tal 4. Th rf puls lngth is aout 1. ms, th powr gain in ach cavit is 4kW with acclrating graint of 5MV/m. Th misalignmnt rror for cavit is mo than 1 mm, an total machin AC powr is somwhat aov 100MW. Compa with th ILC paramtr lists of T. Raunhimr [], th Vr Low Charg Cas propos in this papr is clos to his Low Charg Cas, howvr, if th sam amping ring is us, thir spac charg tun shifts a th sam (aout 0.1, too larg), an that is to sa that if 17km amping ring is us it is vr ifficult to liminat th spac charg ffct from th am paramtr choic. From this conclusion, w strongl propos to incas th amping ring s nrg from 5 GV to 7 GV for a 17km amping ring. Tal. amping ring paramtrs. Tal 4. Main Linac paramtrs. 4. COCLUSIOS In this papr linar collir sign procu is illustrat an a Vr Low Charg Cas is propos for ILC sign. Th author suggsts strongl to incas th amping ring s nrg from 5 GV to 7 GV for a 17km amping ring. Rfncs 1. ITRP, J. Gao, TESLA Rport 00-1, 00.. T. Raunhimr, talk givn at th 1st First ILC Workshop, Japan, ov. 1-15, 005. ILCAW0806 4

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