Low Proton Energy Running. Adiabatic damping and aperture limitations.

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)