beamstrahlung on the septum blade
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Karsten Büßer
Beamstrahlung on the Septum Blade
01.04.2003ECFA/DESY Workshop
Amsterdam
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 2
The Extraction Line Problem
Incoming Beam
Outgoing Beam
Beamstrahlung
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 3
Beamstrahlung Distributions
Realistic Beam Effect of 10 σ offset
N. Walker (Prague):
Expectation: Power on septum blade can reach several kW
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 4
Questions
Formation of a working group to revisit the design of the extraction line. First Meeting on December 3rd 2002 identified the following questions:
• Septum magnet design
• Failure modes
• What power can the thin blade cope with ?
• Reliability of electro-static separators
• IR is a highly charged environment
• Power loss from the charged particle extraction ?
• Is a (small or large) crossing angle a solution ?
• 800 GeV upgrade
How much energy is really deposited in the septum blade ?
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 5
All I am going to present is right out ofthe press and is therefore to be considered
VERY PRELIMINARY
Disclaimer
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 6
Simulating the Extraction LinePart of the extraction line included in BRAHMS:
Shadow:• Distance from IP: 45m• 2m long• 5mm thick• 7mm vertical distance from nominal beam (~156 µrad)• Copper
Septum Blade:• Distance from IP: 47m• 16m long• 5mm thick• ~7mm vertical distance from nominal beam• Copper
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 7
Realistic BeamsSimulation of the complete machine done by Glen White.
Using:• LINAC: PLACET (D. Schulte)• BDS: MERLIN (N. Walker)• Beam-beam: GUINEA-PIG (D. Schulte)
Takes into account:• Simulation of feedback loop• Orbit injection errors into LINAC• Wakefield effects in LINAC• Vibration of quads in BDS• Energy spread of e- due to undulator• Resolutions of BPMs• Jitter on kicker signals
Beams and backgrounds are available through database athepwww.ph.qmul.ac.uk/lcdata
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 8
Nominal Beam
• Total average Beamstrahlung power: ~360 kW
• Integrated power in septum blade area: ~60 W
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 9
Realistic Beam
• Feedback system brings beams into stable collisions after ~100 BX
• Total average Beamstrahlung power: ~500 kW (TDR 360 kW !)
• Integrated power in septum blade area: ~35 kW
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 10
Colliding with the Septum
5 GeV Photon
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 11
Nominal Beam
• Shadow:Average deposited power: ~40 W
• Septum blade:Average deposited power:~0.3 W
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 12
Realistic Beam
• Shadow:Average deposited power: ~15 kW
• Septum blade:Average deposited power:~80 W
01.04.2003
Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 13
Conclusion
• Under realistic beam conditions, 30-40 kW of Beamstrahlung are emitted under vertical angles larger than 0.155 mrad.• Roughly half of the emitted energy is deposited in the septum shadow.• Septum blade receives on average 80W.
→ Information from Efremov: 15 kW has to be cooled away from septum blade due to normal operation.
→ Septum will probably undergo no mechanical damage.
→ 40 kW of Beamstrahlung will irradiate the septum environment.
To be done• Check backgrounds for the detector.
→ Backscattering
→ Pairs, neutrons with realistic beam• Check charged particle extraction losses.
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