Download - Halo scraping and loss rates at collimators
Halo scraping and loss rates at collimators
F. BurkartF. Burkart R. Assmann, R. Bruce, M. R. Assmann, R. Bruce, M. Cauchi, D. Deboy, S. Cauchi, D. Deboy, S.
Redaelli, A. Rossi, G. Redaelli, A. Rossi, G. Valentino, D. WollmannValentino, D. Wollmann
Outline
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1. Introduction
2. Halo scraping measurements
3. Results of data analysis from measurements
4. Collimation losses during high-luminosity fills
5. Results of data analysis from physics fills
6. Conclusion
7. Future work
Why halo scraping?
• Understand population and repopulation speed of the beam halo at 3.5 TeV
→ extrapolate the results to 7 TeV
→ loss rates at collimators
→ minimum instantenious lifetime of the beams
• Calibrate BLM-signal at primary collimator [Gy/s] to a particle lossrate [p/s]
→ compare to losses seen in collimation region during high-luminosity runs
→ distinguish between hor.,ver. and skew losses
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Halo scraping procedure
• Move single jaw of a primary collimator into the beam halo
• with different step sizes (5 micron, 20 micron, 40 micron)
• at different intensities
• in different machine states (injection, collision)
- measure beam intensity (FBCT) → loss rate
- measure BLM-signals
• Most EoF-studies after physics → beam dumped by BLMs
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Usage of different step sizes
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10 μm step size
5 μm step size
BLM-responseScraping with TCP.D B1, running
sum: 1.3 s
6
C-BLM: 8.5E+11 p/Gy
D-BLM: 1.7E+12 p/Gy
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Signal in TCP.C-BLM dominatedby vertical losses
BLM-response for different running sums
Scraping with TCP.D B1
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1.3s: 8.5E+11 p/Gy
10.24ms: 3.4E+12 p/Gy Loss rate diluted in large running sums
Calibration factor Halo scraping
RS09 / RS06
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5/1/10 6/20/10 8/9/10 9/28/10 11/17/10 1/6/11 2/25/11 4/16/111.00E+11
6.00E+11
1.10E+12
1.60E+12
2.10E+12
2.60E+12
3.10E+12
3.60E+12
1,3s10,24ms
Date
calib
rati
on
fac
tor
[p/G
y]
Variation up to a factor 6.6 → to be understood → impact parameter → error in lossrate due to 1 Hz FBCT-signal
Overview of different scrapings
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ScrapingCollimator
BLM on TCP.C
calibration factor [p/Gy]
1,3serror points
28.05.10 TCP.D6L7.B1 1.9E+11 5.4E+09 4
25.08.10 TCP.D6R7.B2 8.6E+11 4.4E+10 27
04.04.11 TCP.D6L7.B1 1.7E+11 2.8E+10 5
04.04.11 TCP.D6R7.B2 1.3E+11 2.5E+10 6
variation up to a factor 6.6 → not understood
Collimation losses during high-luminosity fills – steady
state
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• Measure BLM signals [Gy/s] on Collimators (TCP.C)
• Measure Beam Intensity (FBCT) [p]
→ steady state lossrate [p/s] (dominated by losses at collimators)
→ calibration factor [p/Gy]
Losses with colliding beams Fill 1722, 336 bunches
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Courtesy D.Wollmann
IR7: ~87%
IR8: ~6%
IR3: ~2.5%IR1:
~1%
Linear scale!
Beam Intensity versus time Fill 1749, B1
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Intensity [p]
14 h
Time [s]
7.6*10^13
7.1*10^13
Loss rate versus time Fill 1749, B1, running average
240sec
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14 h
Time [s]
Lossrate [p/s]
dN FBCT
dt
4*10^8
1*10^8
BLM-signal versus time Fill 1749, B1
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14 h
Time [s]
BLM-signal [Gy/s]
0.0001
0.0006
Calibration factors(stable beams)
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Average value B1: 2.2E+12 p/Gy B2: 1.54E+12 p/Gy Variation : 6,5 (B1), 3,4 (B2)
17421743174417451746174717481749175017511752175317541755175617571.00E+11
1.00E+12
1.00E+13
Beam1Beam2
fill number
ca
lib
rati
on
fa
cto
r [p
/Gy
]
Minimum Lifetime RS09 (1.3 s)
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17421743
17441745
17461747
17481749
17501751
17521753
17541755
17561757
0
10
20
30
40
50
60
70
Beam1Beam2
fill number
min
. li
feti
me
[h
]
• 624 b, 768 b
min=3h
=N FBCT
RBLM
Comparison Min.Lifetime B1 RS09, RS06
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17421743
17441745
17461747
17481749
17501751
17521753
17541755
17561757
0
5
10
15
20
25
fill number
min
. li
feti
me
[h
]
Min. Lifetime for multiturn losses → RS06
Comparison Min.Lifetime B2 RS09, RS06
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17421743174417451746174717481749175017511752175317541755175617570
10
20
30
40
50
60
70
RS06 Beam2RS09 Beam2
fill number
min
. li
feti
me
[h
]
Overview of physics fills RS09
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Fill numb
er
#bunch
e
calibration factor
B1 [p/Gy]
calibration factor
B2 [p/Gy]Peak loss B1 [p/s]
Peak loss B2 [p/s]
min lifetime B1 [h]
min lifetime B2 [h]
1743 624 3.2E+12 2.2E+12 3,28E+09
1,45E+09 6,50 14,40
1744 624 2.4E+12 1.3E+12 6,90E+09
1,02E+09 3,00 20,11
1748 624 1.8E+12 9.3E+11 2.26E09 1.73E+09 9,40 12,10
1749 624 3.0E+12 2.2E+12 7.1E+09 9.6E+08 3,00 21,20
1753 768 1.38E+12
1.52E+12 7.2E+09 9.5E+08 3,60 27,00
1755 768 1.9E+12 1.99E+12
1.49E+09 4.56E+9 18,40 58,90
1756 768 4.86E+11
6.29E+11 1.13E+9 1.6E+09 23,50 22,30
Overview of physics fills RS06
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Fill number
#bunche
calibration factor B1
[p/Gy]
calibration factor B2
[p/Gy]Peak loss B1 [p/s]
Peak loss B2 [p/s]
min lifetime B1 [h]
min lifetime B2 [h]
1743 624 2,40E+12 1,68E+12 6,80E+09 2,74E+09 3,12 7,361744 624 1,82E+12 9,40E+11 1,57E+10 1,70E+09 1,33 11,901748 624 1,27E+12 6,23E+11 3,30E+09 2,17E+09 6,40 9,601749 624 2,09E+12 1,51E+12 1,02E+10 1,65E+10 2,09 1,151753 768 7,80E+11 1,17E+12 1,39E+10 4,00E+09 1,90 6,271755 768 1,37E+12 1,47E+12 2,76E+09 1,14E+09 9,96 23,401756 768 6,42E+11 4,20E+11 1,70E+09 4,20E+09 15,30 6,20
Courtesy D.Wollmann
Conclusion
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Halo scrapings
• For vertical losses BLM at TCP.C shows highest signal
• More scraping experiments needed
• More usable data points per experiment → sufficient loss rate
• Variation of calibration factors (~ 6.6)
Physics fills
• Losses mainly appear at collimators (IR7: ~87%)
• Average calibration factor B1: 2.2E+12 p/Gy
• Average calibration factor B2: 1.54E+12 p/Gy
• Min. Lifetime B1 > 1.3 h (RS06)
• Min. Lifetime B2 > 1.15 h (RS06)
Future work
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• Analysis of other integration times
• Analysis of other BLM-signals e.g. TCHSV (physics fills data, scraping data)
• More scrapings with different step sizes → understand variation of calibration factor
• Scrapings with different optics (squeezed, collision)
• Measure repopulation speed
END
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Thank you for your attention!