accelerator physics and engineering

7/29/2019 accelerator physics and engineering

1/22

EuCARD-PRE-2012-004

European Coordination for Accelerator Research and Development

PUBLICATION

Beam-beam simulations: dynamicaleffects and beam-beam limit for LEP3

Ohmi, K (KEK, Tsukuba, Japan)

07 December 2012

The research leading to these results has received funding from the European Commissionunder the FP7 Research Infrastructures project EuCARD, grant agreement no. 227579.

This work is part of EuCARD Work Package 4: AccNet: Accelerator Science Networks.

The electronic version of this EuCARD Publication is available via the EuCARD web site

or on the CERN Document Server at the following URL :


2/22

Beam-

beam

simulations:

dynamicaleffects

and

beam-b

eamlimitfo

rLEP3

K.O

hmi

KEK-A

CCEL

4Dec,2012


3/22

Paramete

rsofLEP3

givenbyF.Zimmerm

ann


4/22

ParametersofTLEP-H

givenby

F.Z

immer

mann


5/22

3Db

eam-beam

inter

action

!y=1mm,"z=

2.3(LEP3)-1.7

(TLEP-h)mm.For"z>!y,the

beam-beamf

orcevariessig

nificantlyalon

gthebunchlength.

Abunchisd

ividedintoseveralslices

whichcontain

manymacro

-particles.

Collisioniscalculatedslicebyslice.

Strong-strong

V0(s)

V0(s,0

)=

Sexp

:

s

0

H0ds:

=

i=

exp

:

p2 x

,i

+

p2 y

,i

2

s:,

Nsl,

i=1

exp

:V1

0,+

(s,i

),i

(+,

s,i

)V0,+

(s,i

)s:

Nsl,

+

j=1

exp

:V1

0,

(s+,j

)+,j

(,

s+,j

)V0,

(s+,j

)s:

driftbetweenslices


6/22

3D

symple

cticintegratorforslice-

by

-sliceco

llision

!P

otentialisc

alculatedatsfandsb.

!P

otentialisinterpolated

tosibetweensfandsb.

sf

sb

s

i

!Sincetheintera

ctiondependsonz,energykickshouldbe

takenintoaccountd!/dz.

!Werepeatthes

ameprocedu

reexchangingparticleand

slice.

sf

sb

s

i


7/22

Potentia

landlin

earkick

ofhe

slice

-by-slicecollision

potentialisinterp

olated.

potentialatcente

rof

slice,BAD

metho

d

KEKBcase

K.Ohmietal.,PRST7,104401

(2004)

ky

=

2

(s)/y

2

=

py

/x

j

(s)=

j(sb)+

j(sf)

j(sb)

sf

sb

(s

sb)

j

(s)=

j

(sc

)


8/22

C

onvergen

ceforthe

slicenum

ber

Allparticlesini-thsliceare

kickedb

ycp

Interpo

lation

ByM.Tawada

KEKBcase


9/22

S

imulatio

n

!R

adiationdampingrate

!

LEP3!xy/T0

=0.036,!s/T

0=0.043

!

TLEP-H

!xy/T0=0.013,!s/T0=0.00875

!T

rackpartic

les1000tu

rns(2000turnsforha

lf

ring),>10xT0/!xy.

!T

argetlumin

ositypercollision

!

LEP3

L=2.675x1033cm

-2s-1

!

TLEP-H

L=

6.125x1032cm-2s-1

!N

macrop=1,00

0,000nzslice=16

8


10/22

Sim

ulation

I(firsttrial)

#x=0.52

,#y=0.5

8

Comparisonbetwe

enIP=1and

2.

ExpectLgeo~2.6

75x1033

Shortterm

behavior

Linit=Lgeo


11/22

Beam

size

#x=0.5

2,#

y=0.5

8

IP=1

IP=

2

Dynam

icbeta


12/22

Firstimpre

ssionofthe

simulationresults

Dynamicbetaworkswellf

orIP=1inthis

operating

point,(

0.52

,0.5

8),b

utd

oesnotfor

IP=2.

Thisisreasonab

leresult.

Luminosit

yforIP=1isnotverygood.

Usually

this

operating

pointshowedhigherlu

minositytha

n

targetoneinKEKB.

Verticalbeams

izeinc

reasesinshorttime.

Largesynchrotrontuneaffects.


13/22

Syste

maticst

udy:Tun

escan

IP=2,#x=0.5

2,scan#y

Head-tailtypeofcoh

erentmotionappear

#y

>0.8.

Incohere

nt#y~0.7

5?

Lgeo~2.6

75x1033


14/22

Tune

scanII

IP=2,#y=0.5

8(0.29

x2),s

can#x

Co

herentmotio

nappearsat#

y>0.8

Lgeo~2.67

5x1033


15/22

Slightuppe

rofinteger

BestL

uminosity,

butlo

werthan

deisgn

.

Lgeo~2.67

5x1033

#x


16/22

Bunch

populat

ionand

specific

luminosity

L=2.6x1033c

m-2s-1

isachievedatNe=1.1x1

012.

Lgeo~

2.6

75x1033


17/22

T

LEP-H

#y=0.58

(0.2

9x2),sc

an#x

16


18/22

TLEP-H

!D

esignluminosity

6

.1x1032isreachable.

!B

etterresultthanLEP3.

!"

sislowerthanLEP3. 17


19/22

S

ynchrot

rontune(LEP3)

!L

uminositydegradationatlarges

ynchrotron

tuneisseen.

#x=0.0

2,#

y=0.1

9

IP=2

18


20/22

S

ummary

!B

eam-beam

simulationshasbee

nperforme

d

forLEP3an

dTLEP-H.

!R

oughtune

scanwas

done.

!Toachieve

thedesign

luminosity

inLEP3,

1

0%morebunchpopu

lationisne

cessaryat

least.TLEP

-Hcanach

ievethedesign.

!T

helargesynchrotron

tunedegra

desthe

luminosityp

erformance.

!

Thetreatme

ntofsynchrotronmotion

andz

dependenceofthebeam

-beamforce

shouldbe

checked.

19


21/22

20


22/22

C

hoiceofoperatingpoin

t

!

("x,"y)=(0.5

1,0.55-0.5

9)isthebe

stfordyna

mic

betainhorizontaland

integrabilityinvertica

lin

everye+e-

collidersw

ithsingleIP.

!

("x,"y)=(0.0

2,0.10-0.1

8)for2IP.Thehorizontal

tunemayn

otbeacceptable.

!

Luminosity

dependenceintunespaceis

showninth

ispresentation.(Nos

trategyfor

optimizationnow.)

21

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