MDI status
2010/2/15 M. Iwasaki
For SuperKEKB MDI group
U TokyoU.
Tokyo, Tohoku U.,
U and KEKMDI group home page
http://hep.phys.s.u‐tokyo.ac.jp/superKEKBMDI/

Introduction
SuperKEKB : To increase the luminosity,
machine p
parameters will drasticallyy changeg
Machine-Detector-Interface design is very important
To assureass re the stable detector operation
IIn this
thi talk
t lk we showh
1. Beam backgroundHi h bHighbeam currentt / S
Smallll b
beam-sizei / StStrong Q-magnets
Qt
2 Space around IR
2.
Two final-Q magnets in both L and R sides
L
Large
crossing
i anglel (83 mrad)d)2

Relationship btw Belle II and SuperKEKB
e- SuperKEKB
HER(e-) axis

Current configuration:
Crossing angle = 83mrad

IP chamber
25.95mrad
Belle II solenoid

15.55mrad67.45mrad

LER
HER

e+ SuperKEKB
LER(e( +) axis

IP chamber : center direction of the LER and HER
Angle btw beam direction and Belle solenoid

Angle btw Belle solenoid
and IP-chamber
IP chamber (mrad)

HER (mrad)

LER(mrad)

41.50

41.50

0

52 82
52.82

30 18
30.18

11 32
11.32

67.45

15.55

25.95

3

Detector BG

4

Nano-beam
Nanobeam option
SR (upstream)

Lower? But affects to the IP-chamber design
Small beam size at final Q
Bending magnets effect? Detector solenoid?

SR (back-scatter)

Much lower
little QCS bending

Radiative-BhaBha

Much lower
Large crossing angle,
but little QCS bending

Touschek

Much higher?
Very small beam size

Beam-gas

Higher?
High current
QCS

HER
beam

Nano-beam

KEKB

QCS

LER
beam

HER
beam

LER
beam

Detector BG status

5

1. Upstream SR
1- GEANT4 simulation by Tokyo (with detector solenoid)
2. Touschek
2- Rough estimation based on life-time (LER)
x20 - 30 higher than the current Belle- TURTLE+GEANT3 simulation by Tohoku
3. BeamBeam-gasgas- Vacuum around IP (+- 2m) will be worse (x10-100) than KEKB- Simulation by Tokyo and Tohoku
4. We did BG run during the last fall Belle run
To get the real data related to the Touschek and beam-gas.
5. Rough BG estimations based on the optics (without solenoid)- Radiative Bha-Bha 1/40
- Backscattering SR 1/800 of the current Belle(it may change with the new optics with detector solenoid)6

1 Detector BG
1.
1 1 Upstream SR
1-1

HER beam-line simulation
New optics without the QC1/QC2 steering magnets (herfqlc4051)
BC1

7

41 5 / 4141.5
41.5
5 mradSR produced z-position

QC1
QC3

QC2

BL1

BC2

Z(m)
E(keV)
25keV

SR E vs produced z-position
Average SR E = 0.5keV

10keV

QC1
QC2
<E>=0.6keV <E>=0.5keV
IP<E>=0.7keV

BC1<E>=0.6keV
BC2 / QC3
<E>=0.3keV

BL1<E>=0.4keVZ(m)HER beam-line simulation
X at IP vs produced z-positionz position

herfqlc4051

x(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipe
R = 1cm

8

HER41 5 / LER 41
HER41.5
41.5
5 mradAngle btw
HER and
Solenoid= 41.5 mradsolenoid
HER beamZ(m)Y at IP vs produced z-position
y(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipe
R = 1cm

SR profile in y-direction is very narrow
Z(m)HER beam-line simulation
X at IP vs produced z-positionz position

herfqlc4038

HER 6767.45
45 / LER 15.55
15 55 mrad

x(cm)
QC1

QC2

BC1

BC2

QC3

9

BL1

Beam pipe
R = 1cm

Angle btw
HER and
Solenoid= 67.45 mradsolenoid

SR profile in x-direction doesn’t change

HER beamZ(m)Y at IP vs produced z-position
y(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipeBi
R = 1cm

SR profile in y-direction becomes wideZ(m)IP chamber and SR

LER e+ beam

HER e- beamxz

10

SR (x<0) can be stopped
with these edges

Summary of SR BG

11- Average SR energy is low enough (< 1keV)- No direct SR hits to the IP-chamber Be-part from HER- If we choose the previous design of 67.45 /15.55 mrad angles,
SR from vertical bending magnet (BC1) may hit
the beam pipe (spread in the y direction )To Do
1. Implement the IP-beam pipe / PXD in the simulation
2 Estimate the energy deposit to the IP
2.
IP-chamberchamber crotched parts
3. LER simulation

12

1 Detector BG
1.
12 P
1-2.
Particleti l BGKEKB BG study
KEKB beam-gas simulation
SuperKEKB beam-gas simulation

Particle BG studies
1. BG study with single e+ or e- beam
To get the real data related to the Touschek and beam-gas.
we did BG studies during the last fall Belle run
1-1 To see the Touschek effect we change the beam-size
1 2 To see the Beam
1-2
Beam-gas
gas effect,effect we change the Vacuum level
1-3 We also change the Vacuum level around IP((The vacuum level at SuperKEKB
pwill bex10-100 worse than current KEKB)
2. MC simulations
2-1 To estimate the BG level at SuperKEKB, we prepare theBeam-gas and Touschek simulations
 Important information to design the maks
2-2 To evaluate the MC simulation, we prepare theBeam gas and Touschek simulations for KEKB
Beam-gas Compare the real data13

BG-study : Vacuum bump
CDC current

S.Sugihara

2009.12.7 19:00-21:20(HER)
Vacuum level at D12 and D1(arc and upstream
pstream IP sections)affects to the detector BG level

Vacuum level
D7/8
D6

D3

D9

D12
D01

14

CDC current

SVD PIN diodeBG-study :Change IP
Vacuum15

2009.12.17 HER (IP)HER Life-time・

Change the IP vacuum levelwith
ith NEGs near the IP(HER downstream)

Bad IP vacuum level affects
to the beam life time, but
not affects to the detector BG

Vacuum at H24 (near IP, HER down stream)

S.Sugihara

KEKB Beam-gas simulation

16

H.Nakano (Tohoku)

In this simulation, we implement the masks
LER beam
01700 1800

2700 2800
3007

4 masks at each places

SVD dose and Beam-gas scattering locationH.Nakano
Coulomb (change direction)

Bremsstrahlung (change energy)

SVD dose

SVD doseIP

IP

The masks are working!
masks

ToDo 1. Start KEKB Touschek simulations
2. Compare BG-study data and simulations
3. Start SuperKEKB simulations

17

18

2 Space for IR
2.

Space for IP region
Little space !!

19

Angle btw
IP-chamber andSolenoid= 25.95 mrad

Little space around IR because- There are two Q-magnets in both L and R sides- Crossing angle becomes large, and IP-chamber
has crotched structures
2010 Feb. Koike

Space for IP region
Little space !!

20

Angle btw
IP-chamber andSolenoid= 0 mradLittle space around IR because- There are two Q-magnets
Q magnets in both L and R sides- Crossing angle becomes large, and IP-chamber
has crotched structures
 IR assembly / design of IR components
See K.Kanazawa’s talk2010 Feb. Koike

Space for IP region
Little space !!

21

Angle btw
IP-chamber andSolenoid= 0 mradWe can only put the 1-2 radiation length
heavy-metal mask to protect the detector

We need to evaluate the particle BG(Beam-gas(Beamgas and Touschek) ASAP
2010 Feb. Koike

Space for IP region
Little space !!

22

Angle btw
IP-chamber andSolenoid= 0 mradTo save the space, we design
the IP-chamber cooling method
without this manifold

Currently we prepare
prototypes for the cooling test

2010 Feb. Koike

23

The beryllium chamber• The central part of the IP chamber is aytube
double-wall beryllium• Two tubes are supported by ribs
– KeepKththe ttwo tubes
t b with
ith uniform
ifgap.
– Control the liquid flow (?)• There are manifold at both ends.

T.Tsuboyama

24

Example 1gogreturnA

B

C

T.Tsuboyamay• The
Th coolant
l tfrom the inlet go
to in one slot tothe end. It
returns throughganother slot tothe exit.
• Two tubes in
the manifold.
• A fear of nonuniformity of the
flow.
flow

Summaryy25

1. Detector BG
1-1 SR- To
T design
d i theh IP
IP-chamberh b we start SR simulationsi l i
1-2 Particle BG- We did BG-study related to the particle BG- Currently we try to do the KEKB particle BG simulation
to comparepthe MC and data
- We are constructing the SuperKEKB particle BG simulation
 Important to design the mask
2 W
2.
We havehlittlelittl space aroundd IP
2-1 New cooling design to reduce the IP-chamber size
- We make prototypes for the cooling test
- Will start the thermal calculation soon
put the large
g mask ((onlyy 1-2 radiation length)g )2-2 We cannot p- Need particle BG simulations as soon as possible

Schedule
FY2009

2010

2011

2012

26

2013

Decision of the accelerator
baseline option

2014
First beam

R&D of IR assemblyy ((~1Y))
IP beam pipe design (~1.5Y)
BG simulation, HOM calculation
coolingg system,y, support,
pp , …

IP beam pipe fabrication (1.5Y)
PXD・SVD mounting(3-5M)
Beam-pipe・PXD・SVD
Beampipe PXD SVD installation (3M)
Belle-II rolled in ・QCS connection ・
cosmic-ray test (4M)
Physics run

Back upp

Introduction

28

SuperKEKBSKEKB : To
T increaseitheth luminosity,l iitmachine parameters will drastically change
I
Issuesoff theth MDI :1. Beam background
High beam current / High power SR emission
2. Heating of IR components
High current / HOM / SR
3. Structure design and assembly of inner detectors, beam pipe,andd fifinall magnetst
Place final Q magnets closer to IP / vibration

MDI design is very important in SuperKEKB
In this talk, we’ll show
Detector BG and 2. Space around IP

SuperKEKB
pAccelerator designg- The base design is Nano-beam option
 There are two final-Q magnets in both L / R sides- 7x4GeV beam energies(To solve the problem on dynamic aperture.)- Crossing angle is 83 mrad
to put the final-Q magnets closer to the IP- The QCS chamber radius is 1cm
 to avoid the resonant cavity structure,
our IP beam-pipe radius should be 1cm

SuperKEKB HER beam-line simulation-Construct ¼ of the whole electron ring (~700m)( 700m) for the Beam-gas simulation-Vacuum level = 107 worse than the nominal value（average # beam-gas scattering is 0.002 / ~700m / particle)
Assumed uniform pressure-Input beam-pipe: r=4.5 (ring) 3.5 (QC2) 1.7 (QC1), and 1cm (IP),Thickness=4(IR) or 6mm(ring), material = SUS ( will change later)-# Generate = 5x105event
 107(scale factor for vacuum) x 5x105 (event) corresponds to ~50 bunches- Process : Bremsstrahlung only (will include Coulomb later)

Energy distribution for the produced via Bremsstrahlung
Average E: ~0.3GeV (histogram is scaled to 1-bunch)

E (GeV)HER beam-line simulation

At first
first, we study where (what component) we have beam particle hits
(We turn off the showering process)(Histogram is scaled to 1-bunch)# Hits in the component
IP-chamber
QC1

0.1 particles / bunch hit QC3, 0.1 particle / bunch hit QC2
1 5 particles
1.5
ti l / bunchbh hit QC1  0.4W
0 4W
2.6 particles / bunch hit IP-chamber

E loss in the component (GeV)

HER b
beam
Component Number

To Do : Implement the IP-chamber and masks.
Estimate the particle BG effect to the detectorBG-study : Vacuum bump
CDC current

2009.12.17 LER

Vacuum level
・

D12

D4
D10 D6 D5
D11 D9D3 D2

S.Sugihara

Vacuum level at D2(upstream IP sections)affects to the detector BG level

CDC current

SVD PIN diodeBG-study :Change IP
Vacuum2009 12 17 LER (IP)2009.12.17

t

LER Life-time

・Vacuum at H24 (near IP
IP, LER upstream)

Change the IP vacuum levelwith NEGs near the IP((LER downstream))

Vacuum level at LER upstream
also becomes worse
Vacuum at H01A (near IP, LER downstream)
・

Bad IP vacuum level
not affects to the detector BG
S.Sugihara

Touschek effect2009.12.7 18:10-19:00 (HER)

2009.12.8 15:30-16:10 (LER)

HER Beam current

LER Beam current

Vertical Beam size

Vertical Beam size

Beam life τBeam life τ

1/τ

1/τ

2009.12.8 15:30-16:10 (LER)

2009.12.7 18:10-19:00 (HER)
1/
1/τ

1/
1/τ

1/σy

Beam life time supposed to follow

1/σy2009.12.7 18:10-19:00(HER)
SVD PIN dilde

CDC current

TOF rateσy2009.12.78 15:30-16:10 (LER)()
SVD PIN dilde

CDC current

TOF rateσySpace for PXD and SVD
18 Nov
Nov. 2009
Toru Tsuboyama (KEK)T. Tsuboyama

Number of cables and tubes
Tubes and cables from each side. For the most narrowpart, heat shield will not be minimized.
C bl (cm
Cables( 2)

T b (cm
Tubes( 2)

IP chamber

4 (8 BPM cables)

2 (3 tubes)

PXD

30(power) 5 (signal)

2 (minimum heat shield)

SVD

94 (hybrid)

2 (4 tubes)

Total

133 cm2

6 cm2

The outerTht radius
di off theth SVD supportt willill b
be 14 cm. If we
use 1/3 of the circumference for mechanical support, 2/3
can be used for cables and tubes
tubes.
The thickness, T, of cables and tubes is, then,T = 133/(14*3.14*2*(2/3))=2.2 cm
This is not impossible to design.

Beam pipe mock up
18 DecDec. 2009
T. Tsuboyama (KEK)T.Tsuboyama

The PXD issue• In the present IP region
region, PXD does NOT
have enough space in the forward region.
• The
Th forwardfd manifold
if ld iis an obstacle.
bl• Ip
proposep
to g
get rid of the forward manifold.
• Instead, the coolant should enter and exitfrom the backward manifold
manifold.

T.Tsuboyama

The beryllium chamber• The central part of the IP chamber will be very
similarsa to tthat
at o
of S
SVD2.
– Double wall of thin beryllium pipes.
– Paraffin will be used as the coolant for safety.
y– I assume 200 W is the maximum heat to be
removed.
• HOM power isi very limited
li it d byb design.
d i• Main contribution: Mirror current (No calculation yet).
• With 2 liter/min p
paraffin flow the temperaturepincrease isT=200/((2000/60)*0.78*2.0)=4oC

Viscosity
Heat capacity

2.4*10-3 kg/ms
2 J/gK

Density

0.78 g/cm3

T.Tsuboyama

The SVD2 chamber mockup• The structure is (almost) same as the finalone.
• Made of aluminum.
• Tests were done
– Flow rate (pressure drop) measurement– Heat removal efficiency measurement

T.Tsuboyama

The SVD2 chamber mockup• The structure is (almost) same as the finalone.
• Made of aluminum.
• Tests were done
– Flow rate (pressure drop) measurement– Heat removal efficiency measurement

T.Tsuboyama

1999 test setuppParaffinreservoir
ese oWater Chiller andheat exchanger
Heater control

Pump(hidden)Flow meterpressuregaugesThe beam pipewith temperature
sensors

T.Tsuboyama

Example 2goreturnreturngo

A

B

C• To improve theflflow
uniformity,
ifit
we may needto have twochannels.
• Two tubes at
th manifold.
the
if ld
Two are for
inlet and twofor exit.
• The coolant
shouldh ld bbeseparated at
the nono
manifold end.

T.Tsuboyama

Summary• I prefer Example 1 for its simplicity.
– Let us make a mock up and test.

• Some worry in the temperature uniformity.
– Can the pipe and manifold stand for 4oC
temperature variation: Mechanics simulationnecessary.
– If Example 1 fails, we should go to Example 2.
– Should
Sh ld we go tto E
Examplel 2
2, are ththere bbettertt id
idea
to keep the number of tubes 2?

• If the calculated heat is much larger than 200
W, we must make the gap wider to have moreparaffin flow
flow. (Otherwise(Otherwise, the IP chamber will
be broken by mechanical or heat stress.)

SR simulation- Detector solenoid affect to produce the SR
 We need to check this effect- Current status
C
Constructingt ti theth nano-beamb
optionti bbeam-line
li simulationi l tiWe modify our simulation to implement the solenoid field
QCS

Solenoid

Solenoid (mapped field)

QC1

At first we used the high-current option optics to check this modification.
 We obtain the exactly same results from both two methods.

HER beam-line simulation
IP

e+
e

QC1L
QC2L

BC1L
QC3L
BC2L

BL1L

HER b
beam

HER beam-line simulation
41 5 / 4141.5
41.5
5 mradNew optics without the QC1/QC2 steering magnets (herfqlc4051)

SR produced z-position

SR energy at IP((average
0 5k V)
0.5keV)
QC1
QC2

BC1

BL1
QC3

E(keV)BC2Z(m)SR x position at IP(RMS = 3.5mm)

SR y position at IP(RMS = 0.1mm)

x(cm)

y(cm)

HER beam-line simulation
X at IP vs produced z-positionz position

herfqlc4038

HER 6767.45
45 / LER 15.55
15 55 mrad

x(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipe
R = 1cmZ(m)Y at IP vs produced z-position
y(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipeBi
R = 1cmZ(m)HER beam-line simulation
X at IP vs produced z-positionz position

herfqlc4039

HER 5252.82
82 / LER 30.18
30 18 mrad

x(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipe
R = 1cmZ(m)Y at IP vs produced z-position
y(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipeBi
R = 1cmZ(m)HER beam-line simulation
X at IP vs produced z-positionz position

herfqlc4039

HER 41
41.5
5 / LER 41
41.5
5 mrad

x(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipe
R = 1cmZ(m)Y at IP vs produced z-position
y(cm)
QC1

QC2

BC1

BC2

QC3

BL1

Beam pipeBi
R = 1cmZ(m)K.Kanazawa

Pressure around IP-Summaryy• Pressure within 2m from the IP is of the orderoff 10-55 Pa
P after
ft 12 daysd
off full
f ll currentt run.
• The final ppressure will be around 10-6 Pa.
• The thermal desorption rate and the photodesorption coefficient of a gold plated surface
is not reported. (This perhaps means the gold
surfacefhhas no superiori vacuum property thanhother metals).
x10-100x10
100 higher vacuum pressure than current KEKB

Beam-gas scattering

H.Nakano

Coulomb scattering

Directionchangeyx

profileBremsstrahlung

Energygy

decrease
Magnetyx
Ex

profileH.Nakano
s[m]

Masks
1700 1800

LER beam

2700 2800
3007

04 masks at each places
Horizontal (x<0)
Vertical (y>0)
Vertical (y<0)
Horizontal (x<0)
Next pages: beam profiles at each masks
1700m
y

1800m
x

Mask

2700m
2800m

H.NakanoBeam profile at each masks (without physics process)Beam profile at each masks (Coul)

H.NakanoBeam profile at each masks (Brem)

H.NakanoScatter position and parameter (Coul)

H.Nakano

SVD doseIP

masks
The masks are working!

Scatter position and parameter (Brem)

H.Nakano

SVD doseIP

masks
The masks are working!

まとめ、今後の予定「まとめ」
・Coulomb散乱
Coulomb散乱、bremsstrahlungともに
bremsstrahlungともに可動マスクによって止められている。
・SVDに当たるものは可動マスク以降でSVDに当たるものは可動マスク以降で散乱されたものである。

「予定」
・TouschekのBG量を見積もる。
・実際のdose量、occupancyと比較し、シミュレーションの妥当性を確認する。

H.NakanoFinal Q layout & IP chamber
KEKB

SuperKEKB Nano-beam option

Common QCS for 2 beams

Two-separate Q-magnets for each 2 beams

QCS

QCS

HER
beam

LER
beam

IP chamber

HER
beam

LER
beam

IP chamber

To connect with the separate Q magnets
the IP chamber has branch structures(crotch structures)

 Kanazawa-san’s talkBelle-II IP chamber deign (2009,Aug)
Mask with heavy metal?

- Size / shape : preliminary- Assume 1cm radius to Be straight part beam pipe
 We need to think about the support of the heavy metal masks(~20kg in one side)
They should be supported by SVD and CDC(otherwise, 1cm radius Be pipe will be broken)

From KEKB to Super-KEKB
Strategies for Increasing Luminosity

High-Current
Option((1)) Smallerll y*(2) Increase beam currents(3) Increase yNano-BeamN
B
OptionTwo machine parameter options
Currently 2 machine options are considered: High-current and Nano-beamHigh
g current optionp(LER/HER)

Nano-beam optionp(LER/HER)High current : 9.4/4.1~3/~2

Sh t bunchShortbh lengthlth : 5/3

6/6

Emittance x (nm)24/18

Low emittance : 1/1

y (nm)

3/6

Small  : 0.22/0.22

0.85/0.73 (m)

Small beam size : 34/44 (nm)- Common QCS for 2 beams- QCS magnets location~40cm (L) / ~65cm (R)Little space in L side

Two separate Q-magnets
for each 2 beams

Beam current I (A)B
Bunchh llengthth z (mm)()

Beam size yFinal Q-magnet layout

Little space in both L/R sides

High-current option … Higher SR BG / HOM heatingN
Nano-beamb
optionti… IR assembly
bl iis diffi
difficultlt
67Design Options

Comparison of parameters
KEKB
DesignKEKB Achieved(): with crab

SuperKEKB
High‐CurrentgOptionSuperKEKB
Nano‐Beam
Optiony* (mm)(LER/HER)

10/10

6.5/5.9(5.9/5.9)

3/6

0.22/0.22

x (nm)18/18

18(15)/24

24/18

1/1

y(m)

1.9

1.1

0.85/0.73

0.034/0.044

y

0.052

0.108/0.056(0.101/0.096)

0.3/0.51

0.07/0.07

z (mm)4~75(LER)/3(HER)

6

Ibeam (A)2.6/1.1

1.8/1.45(1.62/0.95)

9.4/4.1

2.96/1.70

Nbunches

5000

~1500

5000

2500

1

1.76 (1.68)

53

80

Luminosity (1034
cm‐2 s‐1)

High Current Option includes crab crossing and travelling focus.
Nano-Beam Option does not include crab waist.