IP Chamber for Belle SVD2
Tetsuo AbeTohoku University— Outline —1) SVD Upgrade2) Beam-induced backgrounds
3) Stress analysis
4) Beam-pipe heating5) Cooling system for the Be pipe6) Schedule
KEKB Review Meeting
Feb. 11, 2003

IP Chamber for Belle SVD2

1/24

Installed in the summer of 2003
✏ Radiation hardness (VA1):
MRad✏ Improvemtns on the electronics✏ Inprovemtns on the DAQ✏ etc.
MRad✏ Radiation hardness (VA1):✏ Pin-hole problem✏ etc.

In current use✏✏cmTetsuo AbeTohoku University

KEKB Review Meeting ➟ Better vertex resolution➟ Higher tracking efficiency

layerslayerscm

SVD2 





SVD1✏
✏



Silicon Vertex Detector (SVD) UpgradeFeb. 11, 2003

IP Chamber for Belle SVD2(BWD; L-side)cm)

IP Chamber for SVD1 (2/24W shield(FWD; R-side)

Be pipe
IPLERcm)

IP Chamber for SVD2 ( 5cm

Al pipeHER

No SR mask to avoid
resonant HOM

W shield
Be pipe
IPTa pipe

Diaphragm-shaped mamifold
to reduce stress on the Be pipeTetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

3/24

Beam-induced Backgrounds
We have studied:[1] Particle background on HER and LERCoulomb)

Beam-gas scatterings in the entire ring (Bremsstrahlung
Beam-chamber interactions around IP (up to QC2’s)
Touschek effect[2] Background from the Synchrotron Radiation (SR) of HER< a few keV~–

(1) Soft SR radiated from the HER beam in the straight section

QCSR (2) Hard SRbackscattering–20 keV

Tetsuo Abe
Tohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

4/24

[1] Particle-background simulation(done by Karim Trabelsi)✏ KEKB lattice model & Materials around IP

GEANT TURTLE simulation✏ Data MC comparison on the SVD1-layer1 doseMeasurement[kRad yr]Simulation [kRad yr]
Brems Coul Touschek
Total
HER

40.5

—40.5

24LER

35.2(23.3)

56.5(6.5)

91.7(29.8)

82(The numbers in () with no contribution from scatterings on materials outside the vacuum chamber.)

The simulation can reproduce the measurement within a factor of a few.

Tetsuo Abe
Tohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

5/241.5 cm)

Dose calculation for SVD2 (Dose [kRad yr]
Layer1

Layler2

Layler3

HER Brems

12.5

3.0

1.9

HER Coul

13.4

3.9

3.5

LER Brems

13.1(9.0)

3.4(2.0)

1.6(0.6)

LER Coul

14.0

1.4

1.0

Touschek

28.8(9.0)

6.7(1.3)

9.7(0.9)

Sum82(58)

18(12)

18(8)Tetsuo AbeTohoku University

KEKB Review MeetingThe expected dose is much less than
the radiation hardness of SVD2
20 MRad .

Feb. 11, 2003

IP Chamber for Belle SVD26/24✏ Based on the two orbits

HORIZONTAL

2

BPM measurements
1

Nov. 7, 2001
May 15, 2002

on Nov. 7 (2001) and May 15 (2002)


























-20

0s [m]mm (in injections)




 

mm,
















QCSL
QC1LE
QC2LE
BC1LE-40

BC3LE

QC3LE ZVQC3LE-60QC4LE ZVQC4LE

QC5LE ZVQC5LE-80

QA2LE

QA3LE-100

QA4LEs [m]-2

QA5LE0QA6LE-20

Nov. 7, 2001
May 15, 2002

QA7LE-40

QCSL
QC1LE
QC2LE
ZHQC2LEBH2LE BH1LE

QC3LE ZHQC3LE-60

QC4LE BH3LE

QC5LE

BH4LE BH5LE-80

QA2LE-100

QA3LE

-2

QA4LE-1

QA5LE

1-1%

cm

BPM measurements

0

QA6LEnm,VERTICAL

20

QA7LE

✏ Beam parameters∆Y [cm]∆X [cm][2]-(1) Dose Estimation for the Soft SR

SR photons generated from each magnet✏ EGS4➟ Improved on low-energy photons (L-edge X-rays) at KEK➟ Photons traced down to 1 keV➟ Electrons traced down to 20 keV➟ Exact geometry of the beam-pipe from the drawing



Tetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

7/24

SVD2 SR Dosefor the Physics-run Orbit on 2001.11.07

  



 
 

— E



Tetsuo AbeTohoku University  E

QC2LEE 

ZHQC2 E 

BC1LE Dose [kRad/yr]
[mrad][keV]

keV)

 



Watt ((BP-geometry cut is applied.)

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

8/24

SVD2 SR Dosefor the Physics-run Orbit on 2002.05.15[keV][mrad]

 keV)

Dose [kRad/yr](BOTTOM)

 
   EQC1LE E 

Tetsuo AbeTohoku UniversityE    

——  E



QC2LE E

ZHQC2

BC1LE

—   E



QC4LE 

Watt ((BP-geometry cut is applied.)

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

9/24

SVD2 SR Dose for the Injection
based on the Orbit on 2001.11.07

(TOP)

(BOTTOM)
   (TOP)  QA7LE

E

QA4LE

 

E

QA6LE

 

EBC1LEE

————————————————

—E  QA3LE 

QA2LE(BOTTOM)





— 

QC2LE

 

 

 

—

Dose [kRad/yr] [mrad][keV] 

QC1LEkeV)

Watt ( (BP-geometry cut is applied.)EETetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD210/24

SVD2 SR Dose for the Injection
based on the Orbit on 2002.05.15[mrad]

Dose [kRad/yr]  (TOP)



— 



[keV]

  

QC1LE

 

keV)



Watt ((BP-geometry cut is applied.) 
 



 (TOP)— 

QC2LE  

(BOTTOM)

 

 

QA7LE

EQA4LE 

EQA6LEE QA3LE 

QA2LE



(BOTTOM)———————————————EEE

Tetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

11/24

kRad yr in physics runs<~

Dose from the soft SR in the SVD2 layer1 is expected to be

kRad yr in injections



which are much less than the SVD2 radiation hardness:

Tetsuo AbeTohoku University

10 MRad on the silicon sensors (DSSD)
20 MRad on the readout chips (VA1)

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

12/24

[2]-(2) Dose Estimation for the Hard SR(QCSRbackscatteringIP chamber)(done by H. Yamamoto)✏ No SR mask in FWD (R-side)
Simulation can predict dangerous modes.
However, the required fabrication accuracy is close to the limit.
We chose to remove the SR mask.
 ✏ Heavy metals

to avoid possible resonant-HOM heatingsin the taper section



20 kRad yr(much less than the radiation hardness of SVD2)

Tetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003

λ [mm]IP Chamber for Belle SVD2

13/24

102

Photon Absorption Length
AlAuTaW

101-1

10-2

10-3

1010102

Energy [keV]Tetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

14/24

Stress Analysis
The heavy-metal shield leads to a large amount of stress in the joint section.
The final design has been checked by IHI using FEA.



Tetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD215/24

Finite-Element Analysis (FEA)✏ Based on the 3-dimensional SOLID model with an approximation:
Cylindrically symmetric around the beam axis✏ Single support at the flange✏ Inside: vacuum, the cooling gap: 2 kgf cm , outside: 1 atm✏ (calculated stress)

1.15 for earthquakes✏ Static analysis
UTS ,



min





✏ Definition of the permissible amount of stress:
YS

UTS: Ultimate Tensile Stress

XX

StressUTSYSX

YS: Yield Stress

0.2%
Tetsuo AbeTohoku University

KEKB Review MeetingStrainFeb. 11, 2003

IP Chamber for Belle SVD2

16/24

Results





 

mm with the single support at the flange
mm with the fixed support on the flange

Acceptable for the SVD2 mechanical structure



➟➟

 

[1] Displacement (max.)Hz with the single support at the flange Hz with the fixed support on the flange


➟➟



[2] Proper frequency







Rigid structure (Hz)No dynamic analysis needed for earthquakes



Tetsuo Abe
Tohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

17/24

Permissible limit[kgf mm ]Judgment

Section1.15

Stress (max)[kgf mm ][3] Stress

7.69
7.39

8.84
8.50

12.4
12.4

OKOK

Al (FWD)
Al (BWD)

2.12
1.88

2.44
2.16

2.5
2.5

OKOK

Ta (FWD)Ta (BWD)

2.01
3.36

2.31
3.86

10.5
10.5

OK
OK

Ta welding (FWD)
Ta welding (BWD)

2.01
2.36

2.31
2.71

2.58
3.87

OK
OK

Ta-SUS brazing (FWD)
(BWD)

0.70
0.74

0.81
0.85

––

(OK)
(OK)

SUS-Be brazing (FWD)
(BWD)

0.88
0.74

1.01
0.85

––

(OK)
(OK)

Al-Be(out) welding (FWD)
Al-Be(out) welding (BWD)

1.12
1.05

1.29
1.21

1.88
1.88

OKOK

Al-Be(in) welding (FWD)
Al-Be(in) welding (BWD)

1.42
0.83

1.63
0.95

1.88
1.88

OKOK



Tetsuo Abe
Tohoku University

KEKB Review Meeting







Inner Be (FWD)
Inner Be (BWD)

Feb. 11, 2003

IP Chamber for Belle SVD2

18/24

Estimated using the data of the tensile tests



Tetsuo Abe
Tohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

19/24

The final design has stress under the limit all over the chamber.



Tetsuo Abe
Tohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD2

20/24

Beam-pipe Heating
caused by(1) Synchrotron Radiation
In some cases,➟➟

3.5 W on the SR mask (10 W on the Ta pipe

6 K rise at the tip): conductivity)( : permeability,











Heat:(2) Image current

In case of SVD2,➟ 25 W in the Be section➟ 47 W on the Ta pipe
➟ SUS piece is hidden.

(3) HOM (dominant)(next page)

Tetsuo Abe
Tohoku UniversityKEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD221/24

HOM Heating (incoherent)
simulated with✏ MAFIA➟ Non-cylindrical geometries➟ More CPU time✏ ABCIheating)


7W

8W

BEAST

350 mA

921

10 W

8W

450 mA

1146

10.5 W

11 W

 648(

300 mABEAST

SVD1.2

Tetsuo AbeTohoku UniversitycurrentHeat generated in the Be section➟ Cylindrical geometries only
➟ Used in the estimation of the trapped modes (: estimated with ABCI)ABCI simulation works well.

KEKB Review MeetingFeb. 11, 2003

IP Chamber for Belle SVD2 



HOM loss and heating in the entire IP chamber

22/24









SVD1.2

SVD2 (fixed angle)

Heat(SVD2) Heat(SVD1)



SVD2 (varying angle)

1 5

due to the smoother inner surface of the SVD2 IP chamber
The SVD2 cooling system was designed for– 100 W in the Be section– 100 W in the FWD Ta cone
– 100 W in the BWD Ta cone

Tetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003IP Chamber for Belle SVD2

23/24

Cooling System for the Be pipe
✏ Liquid coolant: normal paraffin(He cooling close to the allowed stress limit) ➟ Chemically equivalent to PF200 (C H) which has been used by CLEO for 3 years➟ Flows in the gap of the double-wall Be cylinder ( mm)➟ Corrosion test has been performed using a Be rod over 6 months.

min (should be







➟



✏ The enough cooling power has been confirmed using the simulation and the mockup.
✏ The enough flow rate has been confirmed using the genuine beam-pipe.
min)Graphite seal
AlSS316
BeBe
EBW

Ta

Braze-2 Braze-1
Al-based Au-based

Braze-1Braze-2

TaLER-side

EBW
HER-sideAl

Tetsuo AbeTohoku University

KEKB Review Meeting

Feb. 11, 2003

IP Chamber for Belle SVD224/24

Schedule
In 2003,

28: Installation of the IP chamber into SVD2

(1) Feb. 17

Jun.: System test & alignment using cosmic ray(3) Jul. 1

Oct.: Summer shutdown(2) Mar.



Tetsuo Abe
Tohoku University

Installation of SVD2 into the Belle detector

KEKB Review Meeting

Feb. 11, 2003