LHC Heavy Ion team papers
at IPAC'13 Shanghai

http://cern.ch/ipac2013-LHC-heavyion

This Web page provides advanced "preprint" versions of our papers, slides, posters, other papers, outreach pages and videos and links to other material giving fuller information about our recent work.   Please follow the links in the titles of the following excerpts from the conference programme.

This page is still evolving, more links will be added.
Please note that the definitive versions of the papers will be available from the conference proceedings Web site.

MOODB201 Proton-nucleus Collisions in the LHC -  Preprint -  Slides  
Contributed Oral  
Location Grand Ballroom 2  
Time Monday, 13-MAY-13 15:00 - 15:20  
Speaker John M. Jowett - European Organization for Nuclear Research Beams Department (BE)  
Abstract Following the high integrated luminosity accumulated in the first two Pb-Pb collision runs in 2010 and 2011, the LHC heavy-ion physics community requested a first run with p-Pb collisions. This almost unprecedented mode of collider operation was not foreseen in the baseline design of the LHC whose two-in-one magnet design imposed equal rigidity and, hence, unequal revolution frequencies, during injection and ramp. Nevertheless, after a successful pilot physics fill in 2012, the LHC provided 31 nb^-1 of p-Pb luminosity per experiment, at an energy of 5.02 TeV per colliding nucleon pair, with several variations of the operating conditions, in early 2013. Together with a companion p-p run at 2.76 TeV, this was the last physics before the present long shutdown. We summarise the beam physics, operational adaptations and strategy that resulted in extremely rapid commissioning. Finally, we give an account of the progress of the run and provide an analysis of the performance. Latest tweets on the p-Pb run (click on the hashtag to relive the history from early January 2013)

Selected news items and outreach materials on the first proton-nucleus run of the LHC. 

Further technical papers and talks on the  first proton-nucleus run of the LHC. 

Links to some of the physics results.

Poster papers

Come and talk to us if you are in Shanghai!


TUPFI041 Operating the LHC Off-momentum for p-Pb Collisions - Preprint - Poster
 
Location Fire Poster Area
Time Tuesday, 14-MAY-13 00:00 - 18:00
Presenter Reine Versteegen - European Organization for Nuclear Research Beams Department (BE)
Abstract The first high-luminosity p-Pb run at the LHC took place in January-February 2013 at an energy of 4 Z TeV per beam. The RF frequency difference of proton and Pb is about 60 Hz for equal magnetic rigidities, which means that beams move slightly to off-momentum, non-central, orbits during physics when frequencies are locked together. The resulting optical perturbations ("beta-beating") restrict the available aperture and required a special correction. This was also the first operation of the LHC with low beta in all four experiments and required a specific collimation set up. Predictions from offline calculations of beta-beating correction are compared with measurements during the optics commissioning and collimator set up.
 
TUPFI025 Bunch-by-Bunch Analysis of the LHC Heavy-Ion Luminosity - Preprint - Poster
 
Location Fire Poster Area
Time Tuesday, 14-MAY-13 00:00 - 18:00
Presenter John M. Jowett - but main author is Michaela Schaumann
Abstract After the first run in 2010, the LHC continued its heavy-ion operation with collisions of lead nuclei in late 2011. The beam dynamics of those high intensity lead beams are strongly influenced by intra-beam scattering (IBS), especially on the injection plateau. Each batch injected from the SPS spends a different time at injection, introducing significant changes from batch to batch. Within the batches there is an even larger spread imprinted by the SPS injection plateau. This results in a spread of the luminosity produced in each bunch crossing. The particle losses during collisions are dominated by nuclear electromagnetic processes, leading to a non-exponential intensity decay during the fill and short luminosity lifetime at 3.5 Z TeV. The luminosity, emittance, intensity and bunch length evolution of the 2011 run was analysed bunch-by-bunch and compared with simulations. Based on this analysis, estimates of the potential luminosity performance at 6.5 Z TeV, after the present shutdown, are given.

TUPFI024 Influence of the ATS Optics on Intra-beam Scattering for HL-LHC - Preprint - Poster
 
Location Fire Poster Area
Time Tuesday, 14-MAY-13 00:00 - 18:00
Presenter John M. Jowett - but main author is Michaela Schaumann
Abstract In the future High Luminosity (HL-)LHC the influence of intra-beam scattering (IBS) will be stronger than in the present LHC, because of higher bunch intensity, small emittance and new optics. The new ATS-optics scheme modifies the lattice in the arcs around the main interaction points (IP) to provide β* values as small as 0.15m in the IP, however those modifications affect the IBS growth rates. In this paper proton IBS emittance growth rates are calculated with MADX and the Collider Time Evolution (CTE) program for two ATS-optics versions, different settings of the crossing angles and required corrections and various beam conditions at injection (450 GeV) and collision (7 TeV) energy. CTE simulations of the expected luminosity, intensity, emittance and bunch length evolution during fills are also presented

 

 

WEPEA061 The First LHC p-Pb run: Performance of the Heavy Ion Production Complex - Preprint - Poster
 
Location Earth Poster Area
Time Wednesday, 15-MAY-13 00:00 - 18:00
Presenter Django Manglunki - European Organization for Nuclear Research Beams Department (BE)
Abstract TThe first LHC proton-ion run took place in January-February 2013; it was the first extension to the collider programme, as this mode was not included in the design report. This paper presents the performance of the heavy ion and proton production complex, and details the issues encountered, in particular the creation of the same bunch pattern in both beams.

 

WEPEA060
 Plans for the Upgrade of CERN's Heavy Ion Complex - Preprint - Poster
Poster
Location Earth Poster Area
Time Wednesday, 15-MAY-13 00:00 - 18:00
Presenter Django Manglunki - European Organization for Nuclear Research Beams Department (BE)
Abstract To reach a luminosity higher than 6×10^27 Hz/cm2 for Pb-Pb collisions, as expected by the ALICE experiment after its upgrade during the 2nd Long LHC Shutdown (LS2), several upgrades will have to be performed in the CERN accelerator complex, from the source to the LHC itself. This paper first details the present limitations and then describes the strategy for the different machines in the ion injector chain. Both filling schemes and possible hardware upgrades are discussed.



 
TUPME046 Performance of SPS Low Transition Energy Optics for LHC Ion Beams - Preprint - Poster
Poster
Location Metal Poster Area
Time Tuesday, 14-MAY-13 00:00 - 18:00
Presenter Yannis Papaphilippou - European Organization for Nuclear Research
Abstract An optics with low transition energy has been developed in the SPS for removing intensity limitations of the LHC proton beam and has become operational towards the second part of the 2012 LHC proton run. This optics was also used for filling the LHC with lead ions during the p/Pb run of the beginning of 2013. The impact of this optics in the performance of the LHC ion beam is studied here, especially with respect to collective effects, at the SPS injection energy. In particular, the potential gain of the increased beam sizes provided by this optics, with respect to losses and emittance blow up due to space-charge and Intrabeam Scattering (IBS) is evaluated. The measured lifetime is compared with the one provided by the Touschek effect and its interplay with RF noise is studied. The models are supported by measurements in the SPS and in the LHC flat bottom.

TUPFI011 Study and Operational Implementation of a Tilted Crossing Angle in LHCb  - Preprint - Poster
Poster
Location Fire Poster Area
Time Tuesday, 14-MAY-13 00:00 - 18:00
Presenter Reyes Alemany-Fernandez - European Organization for Nuclear Research Beams Department (BE)
Abstract The current crossing angle scheme at LHCb interaction point (horizontal crossing angle and vertical beam separation) prohibits the use of the LHCb dipole positive polarity for 25 ns bunch spacing operation since the beam separation at the first parasitic encounter is very small inducing unwanted beam encounters. To overcome this limitation a different crossing angle scheme was proposed in 2007 by W. Herr and Y. Papaphilippou. The new schema implies a vertical external crossing angle that together with the horizontal internal crossing angle, from the LHCb dipole and its three compensator magnets, defines a new tilted crossing and separation plane providing enough beam separation at the parasitic encounters. This paper summarizes the feasibility study of the new crossing scheme, the implementation in routine operation and analyzes the beam stability during the building up of the tilted crossing plane.