LHCf Status Oscar Adriani CSN1,MIlano, 26 Marzo 2013

Summary of operations in end beginning 2013 (after the Torino meeting) Arm2 has been re-installed in the TAN region in December 2012 January-February 2013: p/Pb run Arm2 will be removed from the TAN in April 2013 The Arm2 upgrade for the 13 TeV run will be done in Florence in 2013 in strict collaboration with Japanese colleagues Some more details will be given in the next slides

Re-Installation issues Arm2 has been successfully re-installed in the TAN during the technical stop foreseen at the end of the p/p run December 18 th We have modified the LHCf support structure and cabling to significantly reduce the installation required time Mechanical survey has been done in 2 steps: Internal LHCf survey on ground LHCf survey wrt to LHC: done on December 18 th in the TAN area No big problem of radiation, the installation was completely safe (Thanks to Raffaello and Sako!!!)

Discussions and agreements with ATLAS (I) ATLAS trigger can not be sent to LHCf due to timing problem LHCf Level1 Trigger signal has been sent to ATLAS for the whole p/Pb running period ATLAS has properly prescaled the LHCf trigger signal Prescaling factor depend on the running conditions LHCf has recorded in the data stream all the counters and has used all the signals necessary to off-line identify the common events Event Counter Reset Atlas L1ID Bunch ID

Discussions and agreements with ATLAS (II)

Proton remnant side – Invariant cross section for isolated -rays Using only the LHCf informations

What happens if know the Impact Parameter? Ideal case, assuming that we can precisely know the Impact Parameter b (in fm) on event by event basis

What happens if know the Impact Parameter?

Combination of different impact parameter bins In real life b should be estimated by using the Atlas information (centrality) The difference between models is enhanced by the knowledge of the impact parameter

What happens with LHCf on Pb remnant side? Nominal vertical position ( y=0 cm)

Shifting up by y = +2.5 cm The small calorimeter tower remain in the region not screened by the narrow elliptical shape of the beam pipe at D1 magnet We can take good data with reasonable number of hits!

LHCf operation in p – Pb runs at s NN = 5 TeV Pb p IP8 IP2 IP1 Arm2 p Pb IP8 IP2 IP1 Arm2 Proton remnant side Lead remnant side

LHCf operation in p – Pb runs at s NN = 5 TeV #Events (Millions) p-remnant side Pb-remnant side Beam reversal 20 Jan27 Jan. 01 Feb. 200 Millions triggered events!!!!

Summary of LHCf p-Pb runs L = 0.5x10 29 – 1x10 29 cm -2 s -1 * =0.8m, 145 rad crossing angle Not good for LHCf…. We didnt succeed to get a dedicated high * run due to the lack of time 338p+338Pb bunches (min. T=200ns), 296 colliding at IP kHz trig rate downscaled to ~700Hz 20-40Hz ATLAS common trig Coincidence operation was successful!!! Data both at p-side (20Jan-1Feb) and Pb-side (1fill, 4Feb)

Operation at Pb-remnant side A high multiplicity event (Pb-side) p Pb IP8 IP2 IP1 Arm2 MC (Pb-remnant) 3.5cm, 4.0cm

Proton-Proton Collision at s = 2.76 TeV We also profited of the calibration run at s = 2.76 TeV that has been done following the ATLAS and CMS requests 4 hours operation on 14 Feb successfully done. These data will allow a better study of the energy Scaling by comparing different c.m. energy (0.9 TeV, 2.76 TeV, 7 TeV, 13 TeV)

Data list of LHCf p-p, s=900GeV, 2010 (event flags) p-p, s=2.76TeV, 2013 LHCf triggers p-p, s=7TeV, 2010 (event flags) p-p, s=13 TeV, (2015) LHCf triggers p-N,O, (>2019) LHCf triggers p-Pb, s NN =5TeV, 2013 LHCf triggers p-p 400GeV, p-A at RHICH (???) PHENIX, STAR γ, n π0π0 With ATLAS Orange: Future operations Black: completed operations

x F = E/E 0 Playing a game with air shower development: effect of forward meson spectra DPMJET3 always overpredicts production Filtering DPMJET3 mesons according to an empirical probability function, divide mesons into two with keeping p T Fraction of mesons escape out of LHCf acceptance This process Holds cross section Holds elasticity/inelasticity Holds energy conservation Changes multiplicity Does not conserve charge event-by-event E=E 1 +E 2 E1E1 E2E2 x F = E/E 0 pTpT

An example of filtering π 0 spectrum photon spectrum DPMJET3+filter 2.5x10 16 eV proton ~30g/cm 2 Apart from this game we are in strict contacts with model developers to help them improving their codes. Few dedicated workshops have been organized to put theorists and experimentalists in contact

π 0 spectrum and air shower Vertical Depth (g/cm 2 ) AUGER, ICRC g/cm 2 30 g/cm 2

Other analyses and future activities…. Joint analysis with ATLAS … data ready 14 TeV p-p in 2015 … detector upgrade on going Neutron spectra in 7TeV p-p … analysis on going Light nuclei at LHC, RHIC??? … possibility in discussion

LHCf preparation for the 14 TeV p-p run Calorimeter radiation hardening by replacing plastic scintillator with GSO Production and laboratory tests of the new scintillators in Japan is finished for Arm1 and in progress for Arm2 Beam test at Ion facility (HIMAC) for Arm1 has been done in June 2012 Arm1 has been re-assembled in Florence starting from end of June 2012 Same procedure will be followed in 2013 for the Arm2 detector Upgrade of the silicon positioning measurement system Rearranging Silicon layers for independent precise energy measurement Increase the dynamic range to reduce saturation effects Test Beam at LNS for the absolute energy calibration of the silicon system is being requested

Why neutron measurement is important for CR physics Auger hybrid analysis event-by-event MC selection to fit FD data (top plot) comparison with SD data vs MC (bottom plot) Clear muon excess in data even for Fe primary MC The number of muons increases with the increase of the number of baryons! => importance of direct baryon measurement

Neutron Spectra at 7 TeV pp (models) Model predictions Model predictions smeared taking into account the LHCf energy resolution

Life is not easy….. 1 TeV neutrons simulated with 2 different hadronic interaction models used in the detector simulation

Other possibile future runs? Possibility to use LIGHT IONS in LHC from 2016/2017? Light Ion source setup is ongoing because of SPS interest RHIC run in 2015/2016 is under discussion… Please stand by a little bit to see how things are evolving!!!!

Il calcolo per LHCf A settembre la CSN1 ci ha suggerito di muoversi nella direzione di utilizzare le risorse di calcolo del CNAF (nonostante le richieste estremamente limitate di 15 kEuro) In questi mesi, con laiuto di Vincenzo Vagnoni e con il supporto di Luca DellAgnello, abbiamo sistemato le infrastrutture tecniche necessarie per: Generazione (per almeno 4 modelli di interazione adronica) End2End (trasporto beam-pipe) DoubleArm (simulazione del rivelatore) Compilatori, spazio di storage, creazione degli account e delle code per I jobs, etc. Il sistema ora e pronto per partire

Necessita Almeno 4x10 7 eventi Generazione: 35 kB/event 0.1 sec/event Trasporto: kB/event sec/event Simulazione: 20 kB/event 10 sec/event CPU: Almeno 4x10 9 secondi estendibili a 1.3x10 10 sec se ci fosse la necessità di avere 10 8 eventi per un modello Storage: TB

Come sta andando Siamo in contatto con CNAF per finire di risolvere i problemi tecnici rimasti La procedura e stata faticosa, ma alla fine siamo (quasi) arrivati…. Non mi e chiaro come ora sia necessario procedere con la commissione per pagare le risorse CNAF….

Conclusions Re-installation in the tunnel and p/Pb run went very smooth p/Pb and neutron analyses are on-going Atlas joint analysis is ready to start Arm2 upgrade will be completed in 2013 Computing system at CNAF is available Ready to take data at 14 TeV And…. Possible Light Ions runs at RHIC/LHC are under investigation Next week we will have the LHCf meeting in Nagoya

Spares slides

Miscellanea IV: LHCf computing Lo scorso anno abbiamo presentato un piccolo modello di calcolo per far fronte alle esigenze di simulazione e ricostruzione di LHCf per il run p-Pb di cui siamo responsabili I referee ci hanno finanziato una parte di quello richiesto rimandando a questanno la seconda parte a fronte di stime più precise per consentirci la produzione dei plot per la LOI Il data set per la LOI è stato prodotto interamente in Italia e le tre macchine acquistate sono state fondamentali Abbiamo fatto i primi test di simulazione completa con p-Pb 500 KB per evento e 570 sec/evento con la simulazione completa 20 KB per evento e 22 sec/evento se applichiamo dei tagli cinematici abbastanza duri (eccessivi per quello che vorremmo fare) Una via di mezzo tra queste due, dell'ordine dei 100 KB e 100 sec/evento e' quella piu' realistica senza perdere informazioni di fisica rilevanti. Noi abbiamo bisogno di produrre come minimo 10 7 eventi per ciascuno dei modelli studiati (finora 5) Poichè le stime dello scorso anno, basate sulla sola generazione erano ben più ottimistiche di quello che abbiamo ottenuto ora, chiediamo il completamento delle risorse. Per il disco cercheremo di utilizzare risorse presenti in sezione ma abbiamo bisogno di CPU dedicate 15 Keuro per lacquisto delle CPU

Radiation hardness of GSO No decrease up to 1 MGy +20% increase over 1 kGy (τ=4.2h recovery) 2 kGy is expected for 350nb 14TeV pp) kGy Not irradiated ref. sample Irradiated sample τ~4.2h recovery K. Kawade et al., JINST, 6, T09004, 2011 Dose rate=2 kGy/hour (10 32 cm -2 s -1 )

Proton-remnant side – photon spectrum Small tower Big tower

Proton-remnant side – neutron spectrum Small tower Big tower 35% ENERGY RESOLUTION IS CONSIDERED IN THESE PLOTS

What LHCf can measure in the p+Pb run (2) Study of the Nuclear Modification Factor Nuclear Modification Factor measured at RHIC (production of 0 ): strong suppression for small p t at =4. LHCf can extend the measurement at higher energy and for >8.4 Very important for CR Physics Phys. Rev. Lett. 97 (2006)

Lead-remnant side – multiplicity Please remind that EPOS does not consider Fermi motion and Nuclear Fragmentation n Small tower Big tower

π 0 results: Data vs MC

π 0 results: Data/MC Submitted to PRD (arXiv: ).

distribution Three different approaches used to derive the average transverse momentum, pT 1.by fitting an empirical function to the p T spectra in each rapidity range (exponential distribution based on a thermodynamical approach) 2.By fitting a gaussian distribution 3.by simply numerically integrating the p T spectra Results of the three methods are in agreement and are compared with UA7 data and hadronic model predictions. Two UA7 and LHCf experimental data show the same trend no evident dependence of on E CM S. Y Beam =6.5 for SPS Y Beam =8.92 for7 TeV LHC

Comparison wrt MC Models at 900 GeV

small-η = Large tower big-η =Small tower A jump back to analysis: Comparison btw 900GeV and 7TeV spectra Normalized by the number of entries in X F > 0.1 No systematic error is considered in both collision energies. X F spectra : 900GeV data vs. 7TeV data Good agreement of X F spectrum shape between 900 GeV and 7 TeV. weak dependence of on E CMS Preliminary Data 2010 at s=900GeV (Normalized by the number of entries in X F > 0.1) Data 2010 at s=7TeV (η>10.94) Coverage of the photon spectra in the plane Feynman-X vs P T 900GeV vs. 7TeV with the same PT region 900 GeV Small+large tower

Neutron Detection Efficiency and energy linearity Efficiency at the offline shower trigger Flat efficiency >500GeV % Linear fit Parabolic fit

Energy and Position Resolution X Y Neutron incident at (X,Y) = (8.5mm, 11.5mm) ~1mm position resolution Weak dependence on incident energy We are trying to improve the energy resolution by looking at the electromagneticity of the event

K 0 analysis

K 0 Acceptance