LHC Programme Coordination Home Page

Configuration for the proton-lead-run 2016

Disclamer

The data in this table has been compiled in collaboration with the HI machine experts (especially Michaela Schaumann helped to fill this table with interesting contents). This document is work in progress and will be updated whenever needed or useful.

General remarks

On the 5/10/2016 the SPS succeeded to have a Pb beam with 1.5x10⁸ ions per bunch at the SPS extraction.
To avoid beams dumps by bunches which go below the BLM threshold the beams have to be separated in IP1/5 early enough during the 5TeV run. Might also try to rotate bunches against each other so that bunches go in collision which previously have not been collidging (optimal use of injected beam).
It is discussed if the LHCf run can be done at the end of a standard 8TeV physics run without refilling or in a set of "end-of-fill" runs.
In the 5 TeV run only one beam direction will be used: protons in beam 1 and ions in beam 2.
In the 8 TeV part beam reversal is foreseen. But if things work out badly the beam reversal will be suppressed to acquire more integrated luminosity. The 8 TeV programme will start with protons in beam 1.
The biggest unknown is the beam lifetime which will include a non-burn-off component that is hard to predict, this will influence the fill length and therefore the luminosity delivered.
The turn-around time is expected to be similar to that form the 2015 Pb-Pb run (average ~5 hr)

5 TeV run

Experiments requests


IP1 (ATLAS)
Min bias events	A few kilohertz	Achievable with a few colliding bunches
LHCf data taking		With pileup limited to ???; to prepare for the 8 TeV run
IP2 (ALICE)
Luminosity	0.3-0.6x10²⁸cm^-2s^-1	Was higher before (1.0 x 10²⁸). Minimum number of bunches for pileup 0.5% is 106-213
Minimal number of events	679M	assuming 1.5kHz readout rate (was 2kHz before) and 86% efficiency (LHC and ALICE) : need 6 days
Desired number of events	1000M	assuming 1.5kHz readout rate (was 2kHz before) and 86% efficiency (LHC and ALICE) : need 9 days
Beam direction	Protons in beam 1
IP5 (CMS)
Min bias events	O(10kHz)	Achievable with a few colliding bunches
IP8 (LHCb)
Min bias data		Running with low pileup
Beam direction	Protons in beam 1	Compatible with ALICE request.

LHC configuration


General beam properties
Beam energy	4Z TeV	(5.02 TeV cms)
Ion beam intensity	1.4x10⁸
Proton beam intensity	2.0x10¹⁰
Ion beam emittance	1.3 - 1.5 µm
Proton beam emittance	2.2 µm
Ion beam bunch length	0.09m	depends on the blow up which will be set
Proton beam bunch length	0.09m	depends on the blow up which will be set
RF voltage	14MeV
β beating	1.5%	from simulations
Peak lumi per bunch	2.6x10²⁵cm^-2s^-1	At IP1/5 with β*=11m; being optimistic could be a factor of 2 better.
IP1/5 (ATLAS/CMS)
β*	11m
Half crossing angle	140µrad
Geometric Factor protons	0.986
Geometric Factor ions	0.991
Peak lumi estimate	3.7x10²⁶cm^-2s^-1	Assuming 14 colliding bunches. Being optimistic could be a factor of 2 better.
IP2 (ALICE)
β*	2m	implemented as "Ramp & Squeeze"
Leveling factor	≈20
Geometric Factor protons	0.985
Geometric Factor ions	0.991
Peak lumi estimate	6.4x10²⁸cm^-2s^-1	Assuming 443 colliding bunches. Theoretical peak lumi if ALICE would not be leveled.
External crossing angle	+185 µrad
Internal crossing angle	-122.5 µrad
Total half crossing angle	63 µrad
Magnet polarity	+ / +
IP8 (LHCb)
β*	10m
Geometric Factor protons	0.864
Geometric Factor ions	0.908
Peak lumi estimate	5.7x10²⁶cm^-2s^-1	Assuming 22 colliding bunches.Being optimistic could be a factor of 2 better.
Dipole polarity	positive
External half crossing angle	-230µrad
Internal half crossing angle	-236µrad
Half crossing angle	-466µrad

Filling schemes

Scheme
100_200ns_702p_548Pb_0_480_0_20inj	Maximal amount of collisions in ALICE. Will be used if problems with other schemes are encountered.
100_200ns_702p_548Pb_27_458_0_20inj
100_200ns_702p_548Pb_0_458_22_20inj
100_200ns_702p_548Pb_14_443_22_20inj	Default scheme with some collisions at all IPs.

8 TeV run

Experiments requests


IP1 (ATLAS/LHCf)
Integrated delivered luminosity	100/nb
VdM scan		One for each beam direction
LHCf run lumi:	10²⁸cm^-2s^-1	It is being discussed if the LHCf run can take place at the end of one or multiple high lumi runs.
IP2 (ALICE)
Luminosity	10²⁹cm^-2s^-1cm^-2s^-1	Can read out at 300kHz.
Delivered Lumi	20/nb
VdM scan		One for each beam direction
IP5 (CMS)
Integrated delivered luminosity	100/nb	If 70nb will be delivered this is still acceptable. Less would compromise the physics goals.
VdM scan		At least one with the first beam configuration. Will decide later if a second will be requested during the second part.
IP8 (LHCb)
Integrated delivered luminosity	20/nb
Beam reversal		Equal lumi in both configurations.
VdM scan		One for each beam direction

LHC configuration


General beam properties
Beam energy	6.5Z TeV	(8.16 TeV cms)
Ion beam intensity	1.4x10⁸
Proton beam intensity	2.0x10¹⁰
Ion beam emittance	1.3 - 1.5 µm
Proton beam emittance	2.2 µm
Ion beam bunch length	0.09m	depends on the blow up which will be set
Proton beam bunch length	0.09m	depends on the blow up which will be set
RF voltage	14MeV
β beating	3%	from simulations; the same for both directions;
Peak lumi per bunch (head-on)	7.5x10²⁶cm^-2s^-1	Initial lumi at IP1/5 with β*=0.6. Being optimistic could be a factor of 2 better.
IP1/5 (ATLAS/CMS)
β*	0.6
Half crossing angle	140µrad
Geometric Factor protons	0.739
Geometric Factor ions	0.811
Peak lumi estimate	3.9x10²⁹cm^-2s^-1	Assuming 474 colliding bunches. Being optimistic could be a factor of 2 better.
IP2 (ALICE)
β*	2.0
Geometric Factor protons	0.976
Geometric Factor ions	0.985
Peak lumi estimate	6.5x10²⁸cm^-2s^-1	Assuming 216 colliding bunches. With optimisitic assumption could be higher by a factor of 2 in which case ALICE would be leveled to 1x10²⁹. During the ramp up there will be less or no lumi to ALICE.
External crossing angle	+138 µrad
Internal crossing angle	-75 µrad
Total half crossing angle	63 µrad
Magnet polarity	+ / +
IP8 (LHCb)
β*	1.5
External half-crossing angle	-180µrad	Was changed from -230µrad in order to gain aperture
Internal half-crossing angle	-145µrad
Net half-crossing angle IP2	-325µrad	Was changed from -375µrad in order to gain aperture
Geometric Factor protons	0.598
Geometric Factor ions	0.687
Peak lumi estimate	4.4x10²⁸cm^-2s^-1	Assuming 163 colliding bunches. With optimisitic assumption could be higher by a factor of 2.
Dipole polarity	positive

Filling schemes

Scheme
100_200ns_702p_548Pb_474_216_163_20inj
100_200ns_548Pb_702p_474_216_116_20inj

This web site is owned by the account lpc .