BEAST phase1
H. Nakayama(KEK)on behalf ofBelle2 Beam background group
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)1

Goals of Beam Background Group• Overall goals: Estimate, measure, mitigate, andprotect against beam backgrounds• Background sources
–
–
–
–
–
–

•
•

Touschek effect (Beam size and energy)
Beam-gas interactions (current, pressure)
Synchrotron radiation
Radiative Bhabha scattering (Lum.)
4-fermion final state QED process (Lum.)
Injection BG

Can result in instantaneous damage, long term
damage, or excess occupancy in Belle II
Want to measure all backgrounds, validate MC
primarily during phase 1/2 (BEAST). Use MC to
extrapolate to phase 3.

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)2

Beam BG Group• LEADER, BEAST: S. Vahsen (Hawaii)• BEAST KEK liaison, BG simulation: H. Nakayama (KEK)• Institutes:– KEK, Hawaii, Bonn, Trieste, MPI, Heidelberg, DESY, Wayne, NTU, IFCA,
LAL, IPHC, etc..

• Significant support from accelerator colleagues– Beam loss simulation by SAD– BEAST machine study operation

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)

3

BEAST

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)

4

BEAST phase1/phase2

VXD volume

BEAST Phase 1: Jan-Jun 2016
• Vacuum scrubbing of beam pipe.
• No collisions. Belle will not roll-in.
• Variety of subsystems on fiberglass
support structure• No Belle DAQ, only BEAST DAQ

Hiroyuki Nakayama (KEK)

BEAST Phase 2: 2017 Autumn• Belle rolled in.
• VXD volume••

Partial VXD ladders+ other BEAST phase2 sensors• BEAST detectors in dock space andaround QCS• BEAST DAQ + Belle DAQ

21th ARC (June. 13-15, 2016)

5

BEAST phase1 sensors• Measure BG levels near IP– X-rays, charged tracks,
fast/thermal neutrons,
dosimetry– online feedback to SuperKEKB– offline for analysis• Test and calibration of
diamond sensor for VXD beamabort in phase2/3• First measurements ofSuperKEKB injection BG• First comparison of SuperKEKB
beam-loss simulation withexperimental data

6/13/2016

Detectors
Installed

UniqueMeasurement

PIN Diodes
(USA)

64

Neutral vschargedradiation dose

Diamonds(Torieste)

4

ionizing
radiation dose

Micro-TPCs(Hawaii)

4

fast neutron
flux++

He-3 tubes(Canada)4

thermalneutron flux

Crystals(Italy, Canada)

6 CsI(Tl)
6 CsI
6 LYSOEM energy
spectrum,
Injection BG

BGO crystal(Taiwan)8

luminosity“CLAWS”(Germany)

8

Injection BG

SystemBEAST II Phase 1, BPAC Review at KEK

6

BEAST Phase1 sensors at IP
PIN diodes

LYSO/CsI
crystals

He3 tubes(thermal neutrons)

BGO crystals
Diamonds

CLAWS
scintillators

Micro TPCs
（fast neutrons）

Various measurements (fast charged particle, high-energy photons,
thermal/MeV neutron, dosimetry, etc..) to validate beam loss simulation
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)7

October 2015

Belle2(=BEAUTY)(C) DisneyBEAST
6/11/2016

BEAST II Phase 1, BPAC Review at KEK

8

November, 2015
IP shield installation

6/11/2016

BEAST II Phase 1, BPAC Review at KEK

9

Snug fit in the BEAST cave

Photo credit: Tom Browder
6/11/2016

BEAST II Phase 1, BPAC Review at KEK

10BEAST DAQ

3 BEAST racks in B4 DAQ room,
controlled from B3 BEAST booth
1 expert shift + 1 operator shift in B3
Up and running since Jan. 2016
Hiroyuki Nakayama (KEK)

BEAST DAQ team

21th ARC (June. 13-15, 2016)

11

BEAST display in SuperKEKB control
Provides BEAST sensor trend graph,
Injection BG timing structure, etc…

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)

12

BEAST machine studies in phase1• May 16-18, 23-25 (~1.5 shift x 6days)
1. Touschek study• beam size scan, N_bunch scan

2. Vacuum bump study• NEG heating, increase pressure for x100~1000

3. Collimator study• Impact on BEAST BG and beam life time

4. Injection BG study• Time structure, dependence on injection parameters/efficiency

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)13

1. Touschek Studylargebeam size

small
beam size

ECK=0
I=180mA
I=360mA

ECK=0.25 ECK=0.50 ECK=0.75 ECK=1.0

1~4.
current
sweep(vary
Nbunch)I=540mA
I=720mA

5. current
sweep(constantbeam size)

6. size sweep

6~9.
current
sweep

7. size sweep
8. size sweep

Beam
size
blowup9. size sweep

10. chromaticity sweep
11. collimator scan

For HER, we used orbit bump instead of Emittance Control Knob.
For HER, we measured at 160,320,480,640mA.

14

LER sigma_y (X-ray)

LER beam size blow-up
May 17th

160
140
120
100
80
60
40
20
0

25% Nbunch
50% Nbunch
75% Nbunch
100% Nbunch

0

200
400
600
LER current (mA)

0

0.05

0.10

800
0.15

Bunch current/ bunch spacing (mA/bucket)

KEKB (early stage)

Early stage of KEKB: blow up
at 0.04mA/bucket
KEKB after aging (2001): blow
up at 0.12mA/bucket

SuperKEKB LER has achieved same level as KEKB(2001) in mid May.
Hiroyuki
Nakayama(KEK)(June.
13-15, 2016) magnets installed in June.
Further
mitigation
has achieved 21thby ARC
many
permanent

15

Beam size scan
BG
Touschek

Non-Touschek

0

1/sy

We can separately measure Touschek BG and other BG
by fitting BG vs. 1/sy plot with a linear function.
Y-intercept of fitted line corresponds to non-Touschek BG
component. (1/sy=0  sy=Inf.  no Touschek)
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)16

Beam size scan (BEAST He3 tubes)
LER

HER

BG response on beam size clearly seen.
 Evidence for Touschek BG contribution !
Quantitative comparison with SAD/GEANT4 simulation ongoing
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)17

2. Vacuum bump study
D2

D1

D2

D1

D12

D3

D3

D12
Wig
gler

x100~1000 pressure~1 hour/position

LER

Wig
gler

HER

Wig
gler

6 positions

7 positions

Fuji

Fuji

Short sections (4 sections) in D2(need tunnel access each time)
Fuji straight section,
Oho/Nikko wiggler sections

4 arc sections,
Fuji straight section,
Oho wiggler section

Special thanks to SuperKEKB Vacuum group

Vacuum bump study results
LER: Vacuum bump in D02 sections has impact
on BEAST BG, but other position did not.
HER: Vacuum bump in all position has impact
on BEAST BG.
• These observations are consistent withprediction by SAD simulation.

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)19

SAD prediction of Beam-gas BG
HER

LER

P=10nTorr(uniform)assumed

P=10nTorr(uniform)assumedBeam-gas scattered positionof IR beam loss [m]Beam-gas scattered positionof IR beam loss [m]Coulomb: mainly from ~40m
Brems: mainly from ~20m and ~120m
No contribution from other positions

Coulomb: from whole ringBrems: mainly from < 150m

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)20

3. Collimator study
D12

LER

HER

4 parameters

16 parameters
D06

D09

SuperKEKB-type

KEKB-type

D06H3 IN/OUT
D06H4 IN/OUT

D12H1-4, V1-4
D09H1-4, V1-4

Hiroyuki Nakayama (KEK)

Special thanks to SuperKEKB Vacuum group

21th ARC (June. 13-15, 2016)21

Collimator study results
D06H3OUT is found to be effective to reduce
BEAST BG
This collimator is also effective to reduce
injection BG
HER collimators are not effective to reduce
BEAST BG
When HER collimator is too narrow, it even
INCREASE the BEAST BG
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)22

LER collimator optimization
Inj. BG seen

Inj. BG seen

D06H3OUT

No inj. BG

No inj. BG

CsI BG
I_LER

As we change D06H3OUT width from 24mm to 17mm,
BEAST CsI BG shows step-like decrease at every time collimator get narrower.

This is the clear evidence of BG suppression by the collimator!
When we make it further narrower, from 17mm to 16mm at 16:48,
we observed beam life time decreased. This should be the minimum width.
We optimize each collimator width like this.
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)23

4. Injection BG study• Important for Belle2 Pixel detector• Veto window shape should be determined by injection
BG time structure Compare good/bad injection efficiencychanging septum angle, vertical steering magnets, andinjection phase to have bad injection efficiency

 CsI crystal/CLAWS scintillator observed
interesting time structure– Spikes at every ~0.5ms can be explained bysynchrotron oscillation (~2kHz)
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)24

Injection BG on BEAST crystals
LER

HER

Inj. eff.= 95%

Inj. eff.= 95%

Inj. eff.= 70%(phase shift)Inj. eff.= 50%(phase shift)

5ms

5ms

Live BEAST crystal waveforms are now available on SuperKEKB
control panels. Please use it for injection tuning.
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)25

Summary• BEAST phase1 machine study very successful• Detailed analysis ongoing to give comparison
with SAD+GEANT4 simulation• We will repeat similar studies in phase2 with
BELLE detector + BEAST phase2 sensors, andextrapolate it toward phase3

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)26

backup

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)27

HER Vacuum scrubbing progress

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)28

Beam size scan (BEAST CsI crystal)
LER
BG/I^2HER
BG/I^2

LER BG vs. collimator

As we change D06H3OUT width from 24mm to 17mm,
LYSO/CsI BG shows step-like decrease at every time collimator get narrower.

This is the clear evidence of BG suppression by the collimator!
When we make it further narrower, from 17mm to 16mm at 16:48,
we observed beam life time decrease.
Which means this should be the minimum collimator width for D06H3OUT.
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)30

LER Injection BG vs. collimator
12.5Hz inj.

5Hz inj.

Run #5006 was meant to find a effective collimator to mitigate injection BG.
We found D6H03OUT is effective to suppress injection BG on CsI crystal.
Actually, it is the same collimator which is effective to suppress BG
from the stored beam.

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)

32

BEAST Phase2 sensors

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)

33

BEAST Phase2 study• Phase2 is most similar to phase3, but still different
1. “Detuned” optics with smaller IR beta functions (less SR, Toucheck, Beam-gas)
2. Worse vacuum level (more Beam-gas)
3. Smaller luminosity (less RBB/2-photon)
4. VXD ladders at phi ≠ 0 is missing in phase2• We need some extrapolation– For 1, simulation/measurement comparison with detuned optics tells us how
much we can believe simulation with final optics• Collimator secondary shower effect can be measured at phase2.
– For 2. and 3. extrapolation is rather straightforward.
– For 4, beast sensor measurements at phi≠0 is important.

• Separate measurement of each BG sources is important– Vary beam size , vacuum level , luminosity to disentangle Touschek, BeamGas,
RBB and 2photon (same approach with 2010 BG study)– Validate simulation results with measurement
Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)

34

BEAST Phase2 study• Need all sub-detectors DAQ running (at random trigger)– global Belle II DAQ (partial VXD, CDC, TOP, ARICH,BKLM,EKLM, TRG)
– Extrapolate measured each sub-detector BG level to phase3– Sub-detector DQM records are useful for analysis• Other commissioning items during phase2 period– Slow control (EPICS) communication, timing signals connection btw
SuperKEKB-Belle2, beam abort/injection interlock– VXD CO2 cooling, injection noise damping-time measurement, PXD
ROI finding etc…
– Collimator optimization study• Simulation/measurement comparison with various collimator settings• Develop strategy how to reach optimal collimator setting

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)

35

VXD Detector Systems in phase 2• FANGS: Covering 90º , 180º , 270º in φ, full acceptance in θ
• CLAWS: Covering 135º , 225º in φ, full acceptance in θ
• PLUME: Covering 135º , 225º in φ, partial acceptance in θ

6/13/2016cmarinas@uni-bonn.de

BPAC Review at KEK

36

VXD Detector Systems in phase 2• FANGS: Covering 90º , 180º , 270º in φ, full acceptance in θ
• CLAWS: Covering 135º , 225º in φ, full acceptance in θ
• PLUME: Covering 135º , 225º in φ, partial acceptance in θ
+X

PXD

FANGS

FANGS

FANGS

SVD
6/13/2016cmarinas@uni-bonn.de

BPAC Review at KEK

37

Phase2 Background Detectors
sensorcontact p.

numberlocation

DAQ

Belle II PXD

C. Marinas

2 ladders

VXD

Belle II /VXD EPICS

unique measurement

Tasks/
Priority

in-situ occupancy, full Belle II
tracking, vertexing

1,2 (4)

Belle II SVD

K. Nakamura

4 ladders

VXD

Belle II /VXD EPICS

diamondsensors

L. Vitale

8 diamonds

VXD

Belle II monitor DB& BEAST EPICS

ionizing dose in VXD
 BEAM abort

1,2 (4)FANGS“LHC style” silicon
pixel sensors

C. Marinas

3 arms15 chips

VXD

BEAST EPICS

MIPs & x-rays > 10 keV @ 40 MHz 
Synchrotron x-ray spectrum

1,2,4

CLAWS
Scintillators w/
SiPMTsF. Simon2 ladders

VXD

BEAST EPICS

X-rays or track counting w/ 1-ns
timing  injection background

1,2 (4)

PLUME“ILC style” silicon
pixels sensor

I. RippBaudot

2 ladders

VXD

BEAST EPICS

Two-sided silicon pixels  tracklets
w/ pointing(2), 4

Scintillators +PIN diodes

H. Nakayama
K. Nakamura

40+40

aroundQCS

BEAST EPICS

X-ray and total loss distribution versus
position,  collimator adjustment

3

Micro-TPC nuclear
recoil detectors

S. Vahsen

8

VXD dock

BEAST EPICS

fast neutrons: rate, directional &spectral information4

He-3 tube neutron
detectors

S. De Jong

4

VXD dock

BEAST EPICS

thermal neutrons: rate

4

6/13/2016

BPAC Review at KEK

38

Neutron Detectors in Dock Space
A. Beaulieu

8 x TPC fast neutron detector

A. Beaulieu

4 x He-3 thermal neutron detectors

Ahead of / on schedule:
A. Beaulieu• 4 He-3 tubes in hand already for phase 1.
BPAC Review at KEK• 6/13/2016
Six
more
TPCs
(in
additiontothosein phase 1) ~ to be completed by April 2016.
10/18/2015
Plenary Session, 22nd B2GM @ KEK

39
39

Phase2 collimators

Phase-II collimators
New inphase2

HER
D01: H1, H2, H3, H4, H5
V1

LER
D02: H1, H2, H3, H4
x V1

x xx
D01

D12

In phase3
simulation

x

xx

D02
In phase3
simulation

D03
In phase3
simulation

HER
D12: H1, H2, H3, H4
V1, V2, V3, V4
D11

D04

HER: (D09[H/V]*, D12[H/V]*)
Reuse collimators from KEKB

Newly installed btw phase1/2

D02H4, D02H3; D02HV1
D01H5, D01H4; D01HV1
These are crucial toprotect Belle2 in phase2
and perform collimator
study

D05

D10

In phase3
simulation D06

D09
D08
HER
D09: H1, H2, H3, H4
V1, V2, V3, V4

LER
x D03: H1, H2
x
V1, V2Phase1
LER: D06H3, D06H4

D07

D06H4

xx

D06H1LER

D06: H1, H2, H3, H4

Newly installed before phase3?
D02H2, D02H1
D03H2, D03H1; D03V2, D3V1
D01H4, D01H5, D01HV1

Phase2 collimators• Because of severe budgetary limitation, we cannot install all
collimators before phase2• We have concluded that:
install only horizontal x2(nearest) and verticalx1 (for each ring)• These are still sufficient to protect phase2 detectors and to
perform collimator study– BG loss estimation for phase2 sensor• Touschek BG: tolerable (OK even without any collimator)• Coulomb BG: tolerable (V width should be same width phase3)• Injection BG: don’t know yet, H collimators should be effective– Phase2 Collimator study to confirm our strategy• Secondary scattering from nearest H collimator• Feedback from detector BG levels

Final number of phase3 collimators is under study(Hx2 +Vx1 is not sufficient)SAD Simulation results
LER
sler_1689.sad, sler_1689_d4-8.sad

Touschek(|s|<4m)

Touschek(|s|<30m)

Coulomb(|s|<4m)

Phase3 (all collimators)

0.16 GHz

2.7 GHz

Phase3 (Hx2, Vx1)

4.76 GHz

111 GHz

Phase2 (Hx2, Vx1)

0.09 GHz

2.45 GHz

0.03 GHz

Phase2 (Full open)

0.15 GHz

0.17 GHz

2.48 GHz

HER
sher_5775.sad, sher_5767_d4-8.sad

Touschek(|s|<4m)

Touschek(|s|<30m)

0.32 GHz-

Coulomb(|s|<4m)

Phase3 (all collimators)

0.05 GHz

0.64 GHz

0.001 GHz

Phase3 (Hx2, Vx1)

3.50 GHz

21.5 GHz-

Phase2 (Hx2, Vx1)

0.01 GHz

0.07 GHz

0.01 GHz

Phase2 (Full open)

0.16 GHz

0.23 GHz

0.91 GHz>1GHz loss in |s|<4m is too dangerous

Phase3 background

Hiroyuki Nakayama (KEK)

21th ARC (June. 13-15, 2016)44

Ver. 2015.6.15(12th campaign)

BG loss distribution

Loss wattage= loss rate
* energy of loss particle

LER
(e+)

HER
(e-)

1GeV ,1GHz= 0.16W
LER (4GeV e+)HER (7GeV e-)Rad. Bhabha (BHWide)

0.06 W (0.09GHz)

0.05 W (0.05GHz)

Rad. Bhabha (BBBrem)

0.67 W (eff. 1.0GHz)

0.56W (eff. 0.50GHz)

Touschek

0.05 W (0.08GHz)

0.02 W (0.02 GHz)

Coulomb

0.10 W (0.16GHz)

0.001W (0.001GHz)

Summary for 12th campaignlisting SF<5 only
SF=Safety Factor
12th campaign result

limit

SF

PXD occupancy

2photon:0.9% , SR:~0.2% (10th)

< 3%

3

CDC wire hit rate

170kHz<200kHz

1.3

CDC Elec.Borad n-flux* (averg.)

~0.8

<1

1.3

100 Gy/yr<100 Gy/yr

1

TOP PMT rate

3.5MHz/PMT<1 MHz/PMT

0.3

TOP PCB n-flux*

0.15

<0.5

3

ARICH HAPD n-flux*

0.3

<1

3

ECL crystal dose

4.5 Gy/yr<10 Gy/yr2

ECL diode n-flux*

0.23

<1

4

ECL pile-up noise

4.3/5.8 MeV

0.8 at Belle-I?

CDC Elec.Board dose

KLMs studies are not included

With “combined”
shield at inner ECL
BPAC (Feb. 9, 2014)*neutron flux in unit of1011 neutrons/cm2/yr,
NIEL-damage weighted