low proton energy running. adiabatic damping and aperture limitations
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Low Proton Energy Running
Adiabatic damping and aperture limitations
Proton beam-beam Tuneshift
px Ep rp Ie0 xp Ep
2 e f0 nb p Ep xp Ep xp Ep yp Ep
py Ep rp Ie0 yp Ep
2 e f0 nb p Ep yp Ep xp Ep yp Ep
Iex Ep xpmax2 e f0 nb p Ep xp Ep xp Ep yp Ep
rp xp Ep
Iey Ep ypmax2 e f0 nb p Ep yp Ep xp Ep yp Ep
rp yp Ep
Iep Ep min Iex Ep Iex Ep
Iep Ep min Iemax Iep Ep
Electron Beam Size Matching
Electron Beam-Beam Tune shift
0 500 10000.01
0.015
0.02
0.025
ex Ep Ee0
Ep
GeV
0 500 10000.02
0.03
0.04
0.05
ey Ep Ee0
Ep
GeV
We make the conservative assumption, that the tuneshift should be not larger than for the920GeV/27.5GeV values
ex Ep Ee min ex Ep Ee ex 920GeV 27.5GeV( )
Under these circumstances, the number of protons per bunch becomes proton and electron energy dependent.
Np Ep Ee min Np0
2 e Ee xp Ep xp Ep yp Ep ex 920GeV 27.5GeV( )
re xe Ep Ee
400 600 800 10000
5 1010
1 1011
Np Ep Ee0
Ep
GeV
Luminosity as a function of Proton Energy
L Ep Ee Np Ep Ee Iep Ep nbc Rhg Ep Ee
4 e nb xp Ep yp Ep
0 100 200 300 400 500 600 700 800 900 10000
0.8
1.6
2.4
3.2
4
4.8
5.6
6.4
7.2
8
L Ep Ee0 1031cm
2 s1
Ep
GeV
Lumi-scaling with Energy
First simple Version
Protons of 460GeV with Positrons of 27.5GeV
Concept:• Do not touch the positron magnets in the IR• Thus the e+ IR trajectory as in standard running• Increase Beta functions and emittances by a factor of
two• Minimize distance between p beam envelope and GM
Mirror plate• Move all proton magnets GM-QR10
Beam Optics
xp=4.9m xe = 1.20m
yp=0.36m ye = 0.52m
Np=16 mm xe = 40nm
ye = 6 nm
e-Quadrupoles within 40m of IP not changed
Proton Optics
Beam-Beam Tuneshift
Proton
Trajectories
for 920GeV
and
for 460 GeV
Magnet Positions for 920GeV and 460GeV Proton Trajectories
460GeV Magnet Axis Positions
920GeV Magnet Axis Positions
Top View 460GeV/27.5GeV proton /positron trajectories
2nd Iteration Reduce GM magnets in strength and leave all p-magnets in the nominal proton- positron/electron positions Positron Lattice unchanged, positron IR quads unchanged Positron optics in the arc: assume 60 degree positron/proton IP (-7.5mm radially) Optical Parameters:xp=4.9m xe = 1.20m
yp=0.36m ye = 0.52m
Np=16 mm xe = 40nm
ye = 6 nm
IR Top View
P-Magnets: Nominal positron/electron positions
E-Magnets: Nominal positron positions
IR Top View Close-up
All p-magnets are now at nominal positions
P-magnets axisP-magnets axis
GM GM GN GN GN GA GB GB GB9 QR QR QR QRGM GM GN GN GN GA GB GB GB9 QR QR QR QR
~4mm
P-TrajectoryP-Trajectory
IP
P-Optics
Effort to readjust magnets Discussion with surveillers für die vorgeschlagene "Lösung 2" mit einer Justage von 3-4
Magneten habe ich die folgenden Zeiten kalkuliert:
Aufmaß: 3-4 Standpunkte pro Seite (NR,NL,SR,SL) x 4 = 12-16 Std.
Justierung von 3 Magneten x 4 = 12 Std. Kontrollaufmaß = 12 Std.
Gesamt = 36 - 40 Std.
bei Einsatz von zwei Trupps ergibt sich ein Aufwand von 18-20 Stunden.
Spaeter geht es wahrscheinlich etwas fixer, so daß es in knapp zwei Tagen geschafft würde.
To Do List until PRC in May• Match p Optics for left hand side IR (Bernhard/Alexander)
• Design trajectories for right hand side IR (Joachim) ok
• Positron Optics with 40nm (Mathias)
• Explore alternative p-Optics with larger Lumi: GM weaker, GN-1 GN-2 stronger (factor 2), GA stronger, 2nd GN8 off, need GN9, QR10,QR14?
(Ferdinand) done
• Exact Calculation of e and p trajectories with Mike Seidel’s program (refine Magnet positions if needed) and generate magnet position lists, BPM offsets etc…(Joachim) ok
• Recalculate SR deposition (Boris) for the case the GMs are moved
• Check to which extend magnets can be moved (April 5) (Michael/Peter) this Friday
• Discuss with surveillers, make schedule (Michael/Ferdinand) in progress
• Lumimonitor Acceptance (Uwe/Guenther) no problem for 2nd version without moving GM
• Check nonlinear Field Errors for protons in Low Beta Quadrupoles mainly GA
• correction coil settings for off-axis trajectories ok
• Write Low Proton Energy Running Report (all)