New ALICE Beam Pipe: Injection Protection C. Bracco on Behalf of ABT/BTP Acknowledgment: M....
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Transcript of New ALICE Beam Pipe: Injection Protection C. Bracco on Behalf of ABT/BTP Acknowledgment: M....
New ALICE Beam Pipe: Injection Protection
C. Bracco on Behalf of ABT/BTPAcknowledgment: M. Giovannozzi
Outlines
• Reminder• Assumptions• Aperture and beam envelope:– Nominal injection– Grazing event (MKI failure)– Mis-injection
• Conclusions
Reminder
Reminder
To protect the LHC aperture at injection (bottleneck in the arc) and respect the collimation hierarchy:• LHC injection protection
collimators (TDI, TCLIA and TCLIB) ar at 6.8 s
• TCDI (in the TL) are at 4.5 – 5 s
MG - TREX meeting 5
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-20 -15 -10 -5 0 5 10 15 20
n1 (s
)
Distance from IP (m)
Beam 1 - Nominal - Inj
Beam 1 - After LS2 - Inj
Beam 1 - After LS2 Rev 2 - Inj
18/07/2014
Alice aperture: results - I
b*=10 mqext=170 mradSep=2 mm
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-7 -5 -3 -1 1 3 5 7
n1 (s
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Distance from IP (m)
Beam 1 - Nominal - Inj
Beam 1 - After LS2 - Inj
Beam 1 - After LS2 rev 2 - Inj
M. Giovannozzi
4 s bottleneck in the experiment
Minimum aperture = 13 s (bottleneck in the arc)
Ok!...check MKI grazing failure..
Reminder
90% MKI strength
10% MKI strength
Assumptions• Normalised emittance of 3.5 mm mrad also for postLS2 case
• Optics for protons (minimum n1):b* = 10 m, crossing angle = 170 mrad , separation =2 mm
• Beam envelope: 6.8 sb (what can go through TCDIs and TDI) + 20% beta-beating
• Aperture: Mech.aperture* – Mech.tol.* – Orbit** – Disp.offset***
* Data from ALICE and Massimo** 4 mm *sqrt(b/max(b)) *** Dy*3e-4
Aperture and Beam Envelope PreLS2
TDI
TDI
Nominal kick
Aperture and Beam Envelope PostLS2
TDI
TDI
Nominal kick
Phase Advance Min. Aperture- MKI
Grazing Event (Vertical)
TDI
TDI
Nominal MKI kick
grazing (10% MKI kick)
Grazing Event (Vertical)
TDI
TDINominal MKI kick
grazing (10% MKI kick)
20 sigma
Mis-injection (Horizontal)
Nominal
Mis-injection:x0 = 2.5 mmx0’= 30 urad
Mis-injection:x0 = 2.5 mmx0’= 30 urad
15 sigma
Conclusions
• The new proposed aperture fulfills the n1 requirements of collimation hierarchy: bottleneck kept in the arc and > 7.5 s
• No direct beam impact on the new aperture is expected also in case of the most critical MKI failure (grazing event) or mis-injection