Injector Upgradefor SuperKEKB
Kamitani Takuya (KEK)KEKB Injector Linac
Sector-B

Acceleration
unit

Sector-A

e- Gunfor KEKB

180deg
ARCe- Gun for PF/AR

Sector-C

Sector-1

RF modulator
Klystron
SLED (RF pulse compressor)
Accl. structurese+ generation target

Sector-2

Sector-3

PhotonFactory

Sector-4

Sector-5
KEKB
HER/LER

Energy gain /Acceleration field�
21 MV/m
Accl. structure length� 1.928 m# of Accl. structures� 4 /unit

160 MeV/Total Energy gain
potentiality
e- to HER:�
(160 MeV/unit) (55 accl. units) = 8800 MeV
e+ to LER:�
(160 MeV/unit) (29 accl. units) = 4640 MeV
e- to Target:� (160 MeV/unit) (26 accl. units) = 4160 MeV

KEKB Injector Linac Performance�Electron (e-)�

Positron (e+)�

Beam Energy�
Charge��Emittance (normalized)�
Energy spread (full width)�

8.0 GeV�
1.0 nC/pulse�
800 mm.mrad�
< 0.5%�

3.5 GeV
0.64 nC/pulse( single bunch / pulse )�
2500 mm.mrad
0.5 %

3.0 mA/sec�

1.5 mA/sec��

Injection rate��( single bunch / pulse )�

SuperKEKB Requirements to Injector�

KEKB�

Beam Energy (e-)�
(e+)�

8.0 GeV
3.5 GeV��Stored current (e-)�
(e+)�

�

SuperKEKB��----->�
----->�

3.5 GeV
8.0 GeV !!

NEED Energy upgrade for e+ !
KEKB design� SuperKEKB��
0.9 A ---> 1.1 A --->� 9.4 A !!
1.3 A ---> 2.6 A --->� 4.1 A !!�
Feb. 2002

NEED Intensity upgrade for e-/e+ !

(1) Energy Upgrade
How to increase e+ Energy ?

Two schemes under consideration(A) Higher Acceleration Field scheme��Doubling Acceleration Field (21 -> 42 MV/m)with C-band system(B) Beam Recirculation scheme������Recirculate e+ beamwith Damping ring and beam return line
in synchronous to next RF pulse--> Multi-Beam acceleration in same RF pulse�(primary e- and e+) (high E e+ and low E e+)

(A) Higher Acceleration Field schemeAB

eGunDampingRing

1.7-GeVJ-arc for e–E(e+)=1.0 GeV
Q(e+)=1.2nC

e+ targetC

1E(e–)=3.5 GeV,
Q(e–)=10 nCto target
Q(e–)=5 nC

234E(e+)=8.0 GeV,
Q(e+)=1.2 nCHER
5New C-band units

LERE(e–)=3.5GeV,Q(e–)=5 nC

24 accl. units are Replaced to C-band � (Eacc = 21 -> 42 MV/m)
�(Egain = 160 -> 320 MeV/unit)�(max. e+ total Egain = 4640 -> 8640 MeV)
e+ Damping Ring for smaller emittance and beam size�to fit for smaller aperture in C-band accl.
structures�S-band (2856 MHz) accelerating structureComparison of accelerating structures
S-band accl.
structure

80 19Accl. Field = 21 MV/C-band accl. structure(5712 MHz)

10.7 42(Unit : mm)
Accl. Field = 42 MV/

New accelerating unit for C-band structures

SLED

Wave
guidePulse
Pulse
40 MW40 MW
ModulModulKlystron2
Klystron1
ator2
ator1

Beam

Accelerating
Structures

C-band accelerating structure parameters for 42 MV/m
�
RF frequency (f)�Mode�
shunt impedance (r0)�
Quality factor (Q)�group velocity (vg)�

S-band (present)�
2856 MHz�
2/3 p�
57 MW�
13700�
0.012 c�C-band unit�
5712 MHz
2/3 p
75 MW
9700
0.019 c�

RF power from Klystron�
Power multiplication�

41 MW 4 msec�
3.4 with SLED�

2 x 40 MW 2 msec
3.4 with SLED/LIPS

Acceleration Field (E0)�

21 MV/m�

42 MV/m

(B) Beam recirculation schemeAB

1.5-GeVJ-arc1 for e–
J-arc2 for e+CeGun
DampingRing

E(e+)=1.0 GeV
Q(e+)=1.2nC

e+ target
1E(e–)=3.5 GeV,
Q(e–)=10 nC
to target
Q(e–)=5 nC
for Injection

2345E(e+)=8.0 GeV,
Q(e+)=1.2 nC
HER
LER
E(e–)=3.5GeV,
Q(e–)=5 nC

No significant Upgrade in RF sources & acclerating structures
e+ Damping Ring for synchronization to next RF pulse
e+ beam return line, 2nd J-arc for e+, target-bypass beam line--> Multi-Beam acceleration in same RF pulse�(primary e- and e+) (high E e+ and low E e+)

For the simultaneous acceleration ofe- and e+ beam andlow Energy e+ and high Energy e+ beams
complicated transport line isnecessary.

e- beam fore+ generation
KickerBende+ target
2-1 unit

2-2 unitlowE(0.4 GeV) e+
2-4 unit

Bend
Bend

2-3 unit

highE(3.5 GeV) e+
3.5 GeV e- for LER

2-6 unit

(2) Intensity Upgrade
How much increase ?
How to increase ?

Best Shift (8hours) 2002
Feb.

If LPeak continues for 8 Hours�=> 190 /pb /shift
122.1 /pb /shift is 64 % of it.

Inefficiency(1) TopupFactors(3) Beam Abort &(2) Current Loss
Re-Fill Injection
Injection
during Collision

Topup Injection time

Injection interval ˜ 86 min

Total Dead time for Injection ˜ 12.5 min

eInjection

Linac modeswitchinge+ Injection

Belle & Rings
mode switching
PHYS -> INJ

Belle & Rings
mode switching
INJ -> PHYS

SuperKEKB(present INJ rate)

Beam Currents [mA]Simulated Run status
LER current [mA]

HER current [mA]

12000
10000

[ HER e+ ]dI/dt = 1.5 mA/sec
max current = 4100 mA
lifetime = 150 min[ LER e– ]2.4
dI/dt = 3.0 mA/sec
max current = 9400 mA
2.2
lifetime = 150 min

8000

2T_cycle = 100 min

6000

1.8
T_switch = 1.0 min

T_Collis = 59 min

0Lumi Efficiency = 0.450
1.2

4000

Luminosity normalized by Peak value-2000

1-40000.8-6000

0.6-8000

0.4-10000

0.2-12000
060

120180240300

Time [min]3604200480Luminosity Normalized
by Peak value

2000

T_Belle_HVup = 1.5 min
T_Belle_HVdw = 1.5 min
1.6
T_INJ(e+) = 19.1 min
T_INJ(e–) = 21.4 min
1.4

Improvement By Intensity Upgrade–LER [ e ] Injection rate - Integrated Luminosity Relation

1with improved injection ratee- 15.0 mA/sec (Target Values fore+ 3.0 mA/sec
Intensity Upgrade)dI/dt (e+) = 12.0 mA/s
dI/dt (e+) = 6.0 mA/s
dI/dt (e+) = 3.0 mA/s
dI/dt (e+) = 1.5 mA/s

Luminosity Efficiency

0.80.6

SuperKEKB (Topup)
0.4

with Present injection rate
e- 3.0 mA/sec
e+ 1.5 mA/sec

0.20051015

HER => e+, LER => e–
I_Max_LER = 9400. [mA]
T_Life_LER = 150. [min]dI/dt_LER = VARIED [mA/sec]
I_Max_HER = 4100. [mA]
T_Life_HER = 150. [min]dI/dt_HER = changed [mA/sec]
T_Switch = 60. [sec]T_Belle_HVup = 90. [sec]T_Belle_HVdown = 90. [sec]20

dI/dt_LER [mA/sec]

2530

SuperKEKB(improved INJ rate)

Beam Currents [mA]

Simulated Run status
LER current [mA]

HER current [mA]

12000
10000

[ HER e+ ]dI/dt = 3.0 mA/sec
max current = 4100 mA
lifetime = 150 min[ LER e– ]2.4
dI/dt = 15.0 mA/sec
max current = 9400 mA
2.2
lifetime = 150 min

8000

2T_cycle = 56 min

6000

1.8
T_switch = 1.0 min

T_Collis = 45 min

0Lumi Efficiency = 0.667
1.2

4000

Luminosity normalized by Peak value-2000

1-40000.8-6000

0.6-8000

0.4-10000

0.2-12000
060

120180240300

Time [min]3604200480

Luminosity Normalized
by Peak value

2000

T_Belle_HVup = 1.5 min
T_Belle_HVdw = 1.5 min
1.6
T_INJ(e+) = 6.4 min
T_INJ(e–) = 3.1 min
1.4

New Ideas(1) By Continuous Injection,�������
��

--> No gradual Current Loss (e+, e-)--> No dead time of Beam injection�
except Belle data acquisition VETO (2 ms)--> No dead time of Belle Detector HV Up/Down--> Less injection current (to make up only gradual loss)�present�dI/dt (e- Inj.) = 1.01 mA/s�
<< 3.0 mA/s
dI/dt (e+ Inj.) = 0.46 mA/s�
<< 1.5 mA/s
(assuming LER e- 9.4A, HER e+ 4.1A, lifetime 150min)(GOOD NEWS !!)Test KEKB operation with Continuous Injection (e+ only) was
successful in 2001 Dec. and 2002 Jan.

Continuous Injection
Test

AR
inj.

AR
inj.

AR
inj.

AR
inj.

(2) By Simultaneous Injection of e+/e���--> No dead time of Linac Mode change (e+ <-> e-)--> Perfect constant stored current for e+ and e2-Bunches Operation
1-st bunch -> e- Injection
2-nd bunch -> e+ productionAB

1.0-GeVDamping

eE(e+)=1.0 GeV
Q(e+)=1.2nC

1.7-GeVE(e+)=8.0 GeV,e+ target
C1E(e–)=3.5 GeV,
Q(e–)=5 nC

234C-band

5E(e–)=3.5GeV,

HER
LER

SuperKEKB(Continuous &Simultaneous INJ)

Beam Currents [mA]

Simulated Run status
LER current [mA]

HER current [mA]

12000
10000

[ HER e+ ]dI/dt = 3.0 mA/sec
max current = 4100 mA
lifetime= 150 min
2.4
[ LER e– ]= 15.0 mA/sec
2.2dI/dt
max current = 9400 mA
lifetime = 150 min

28000

T_cycle = till Abort

1.8
T_Collis = till Abort6000

T_switch = none
T_Belle_HVup = 1.5 min
1.6
T_Belle_HVdw = 1.5 min
T_INJ(e+) = 22.8 min
1.4
T_INJ(e–) = 10.4 min

4000
2000
0Luminosity normalized by Peak val.

1.2
Lumi Efficiency = 0.946
1-40000.8-6000

0.6-8000

0.4-10000

0.2-12000
060

120

180240300

Time [min]

360

420

0480

Luminosity Normalized
by Peak value-2000

How to achieve e- Intensity increase��

3.0 mA/sec --> 15.0 mA/sec��already 10 nC e- beam is accelerated
to the e+ generation target�

No problem on Generation of 5 nC e- beam���* Wake field issue* Beam quality issue for the Injection
� (5 nC beam has larger emittance and energy spread !)��(1 nC/pulse)(5 nC/pulse)--> IF it is essential, e- Damping Ring ?

How to achieve e+ Intensity increase��

1.5 mA/sec --> 3.0 mA/sec��

e+ capture section upgrade� � With stronger focusing solenoid (flux concentrator?)��* Beam quality issue for the Injection�
if No Damping Ring(0.6 nC/pulse)(1.2 nC/pulse)Summary1

Energy upgrade for e+ 8.0 GeV injection(1) Higher accelerating field with C-band structures����

Simple Beamline Layout and Operation
Need C-band components R & D� � -> Challenge for High acceleration Field
Higher Cost
(2) Beam recirculation with damping ring���Complicated Beamline Layout and Operation
No need for accl. unit upgrade
Lower Cost

Summary2� �Intensity upgrade(1) e- (x 5 increase) By 5 nC e- beam injection
�5 nC beam generation OK�
Wake effects -> Beam quality OK ?� � ��(2) e+ (x 2 increase) By Adiabatic Matching system
�Need Flux concentrator�(3) Continuous Injection �� --> already OK for Linac�
(4) e+/e- simultaneous Injection By 2 bunches operation
�
Need Fast Kicker