fast beam losses during beam dump process due to ( missing ) lr beam-beam kick
DESCRIPTION
Fast Beam Losses during Beam Dump Process due to ( missing ) LR Beam-Beam kick. LBOC Tobias Baer July, 31 st 2012. Acknowledgements : S. Bart Pedersen, E. Effinger, B. Dehning, M Hempel, M. Schaumann, R. Schmidt, D. Valuch, J. Wenninger. Beam Dump on 8.7.2012 20:46. - PowerPoint PPT PresentationTRANSCRIPT
LHC Beam Operation CommitteeJuly, 31st 2012 1
Fast Beam Losses duringBeam Dump Processd u e t o ( m i s s i n g ) L R B e a m - B e a m k i c k
LBOCTobias BaerJuly, 31st 2012
Acknowledgements: S. Bart Pedersen, E. Effinger, B. Dehning, M Hempel, M. Schaumann, R. Schmidt, D. Valuch, J. Wenninger.
LHC Beam Operation CommitteeJuly, 31st 2012 2
Beam Dump on 8.7.2012 20:46
• Beam dump due to trigger by B2 LL-RF (cryo problem)Strange: Single-turn losses on B1 in before beam dump.
Signal from diamond BLMs in IR7.
1 turn
Dump B1(cut off)
Losses B1
Losses in IR7 for B1 and B2.
Dump B2(cut off)
250mV · 1380b≈ 0.7 Gy/s at BLMEI.06L7.B1E10_TCHSH.6L7.B1 RS1
28.07.2012 10:06.
LHC Beam Operation CommitteeJuly, 31st 2012 3
Event Sequence
Dump trigger by RF for B2 only.IR1
IR6
IR7
IR5
IR3
IR4
IR2 IR8
B2 AGB1 AG
0
Fire M
KD.B
2
8/8 turns
LHC Beam Operation CommitteeJuly, 31st 2012 4
Event Sequence
Perturbation of Horizontal B1 trajectory downstreamof IR5 due to missing LR beam-beam kick in IP5.
B1 H
B1 V
200µm
IR5 IR8 IR1 IR2 IR5
200µm
Turn-by-Turn BPM post mortem data
IR1
IR6
IR7
IR5
IR3
IR4
IR2 IR8
0
Fire M
KD.B
2
8/8 turns
No IR5
bb ki
ck
1/8
LHC Beam Operation CommitteeJuly, 31st 2012 5
Event Sequence
Start of B1 losses in IR7.
0
Fire M
KD.B
2
8/8 turns
IR1
IR6
IR7
IR5
IR3
IR4
IR2 IR8
3/8
No IR5
bb ki
ckLo
sses
in IR
71/8
Pacman structure of beam losses.
LHC Beam Operation CommitteeJuly, 31st 2012 6
Event Sequence
No beam-beam kick in IR2, IR1 and IR8 anymore(some bunches).
0
Fire M
KD.B
2
8/81/8
IR1
IR6
IR7
IR5
IR3
IR8
IR4
IR2
3/8
No IR5
bb ki
ckLo
sses
in IR
76/8
No IR2
, IR1,
IR8 b
b kick
B1 H
B1 V
200µm
IR5 IR8 IR1 IR2 IR5
200µm
Measurement is a convolution of all bunches!
LHC Beam Operation CommitteeJuly, 31st 2012 7
Event Sequence
Losses due to uncaptured beam in abort gap duringMKD rise time observable in IR7.
0
Fire M
KD.B
2
8/81/8
IR1
IR6
IR7
IR5
IR3
IR8
IR4
IR2
3/8
No IR5
bb ki
ckLo
sses
in IR
76/8
No IR2
, IR1,
IR8 b
b kick
Dump l
osse
s
LHC Beam Operation CommitteeJuly, 31st 2012 8
Event Sequence
B2 completely dumped.B1 H trajectory perturbation observable by ADT pickup.
0
Fire M
KD.B
2
8/81/8
IR1
IR6
IR7
IR5
IR3
IR8
IR4
IR2
3/8
No IR5
bb ki
ckLo
sses
in IR
76/8
No IR2
, IR1,
IR8 b
b kick
Dump l
osse
sB2
dum
ped
ADT post mortem data
15µm
LHC Beam Operation CommitteeJuly, 31st 2012 9
Event Sequence
Fire B1 MKD 1.25 turns (=111µs) after B2 MKD.
0
Fire M
KD.B
2
8/81/8
IR1
IR6
IR7
IR5
IR3
IR8
IR4
IR2
3/8
No IR5
bb ki
ckLo
sses
in IR
76/8
No IR2
, IR1,
IR8 b
b kick
Dump l
osse
sB2
dum
ped
Fire M
KD.B
1
10/8
LHC Beam Operation CommitteeJuly, 31st 2012 10
Event Sequence
Losses due to uncaptured beam in abort gap duringMKD.B1 rise time observable in IR7.
0
Fire M
KD.B
2
8/81/8
IR1
IR6
IR7
IR5
IR3
IR8
IR4
IR2
3/8
No IR5
bb ki
ckLo
sses
in IR
76/8
No IR2
, IR1,
IR8 b
b kick
Dump l
osse
sB2
dum
ped
Fire M
KD.B
1
10/8
Dump l
osse
s
LHC Beam Operation CommitteeJuly, 31st 2012 11
Summary & Outlook
• A single-turn beam loss during the beam dump process was observed. The effect can be explained by the missing LR beam-beam kick after a dump of B2, which leads to a B1 trajectory perturbation of several 10µm.
Outlook: • Calculated the expected missing kick and compare it to the BPM
reading.• End-of-fill test with bunch-by-bunch ring BPM acquisition?