LHCf: stato e programmi Oscar Adriani CSN1,Torino, 27 settembre 2012.
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Transcript of LHCf: stato e programmi Oscar Adriani CSN1,Torino, 27 settembre 2012.
LHCf: stato e programmi
Oscar Adriani
CSN1,Torino, 27 settembre 2012
Introduction and contents
Analyses p0 paper accepted by PRD 900 GeV g paper published on PLB Short spot on other analyses
Arm1 preparation for 14 TeV
Beam test at SPS (August-September 2012)
Arm2 preparation for p/Pb 2013 run
LHCf: location and detector layout
44X0, 1.6 lint
INTERACTION POINT
IP1 (ATLAS)
Detector IITungsten
ScintillatorSilicon
mstrips
Detector ITungsten
ScintillatorScintillating
fibers140 m 140 m
n π0
γ
γ8 cm 6 cm
Front Counter Front Counter
Arm#1 Detector20mmx20mm+40mmx40mm4 X-Y SciFi tracking layers
Arm#2 Detector25mmx25mm+32mmx32mm4 X-Y Silicon strip tracking layers
π0 analysis: PT spectra for different rapidity bins“Measurement of forward neutral pion transverse momentum spectra for √s = 7TeV proton-proton collisions at LHC“‘Accepted’ by PRD
Type-I Type-II
Type-II at small tower
Type-II at large tower
Type-ILHCf-Arm1
Type-IILHCf-Arm1
LHCf-Arm1Data 2010
BG
Signal
Preliminary
•Large angle•Simple•Clean•High-stat.
•Small angle•large BG•Low-stat., but can cover•High-E•Large-PT
π0 analysis at √s=7TeVSubmitted to PRD (arXiv:1205.4578).
Type I π0 analysis procedure
Mass, energy and transverse momentum are reconstructed from the energies and impact positions of photon pairs measured by each calorimeter
Analysis Procedure • Standard photon reconstruction• Event selection
- one photon in each calorimeter- reconstructed invariant mass
• Background subtraction by using outer region of mass peak
• Unfolding for detector response. • Acceptance correction.
Dedicated part for π0 analysis
m 140=
R
I.P.1
1(E1)
2(E2)
140m
R
Acceptance for π0 at LHCf-Arm1Validity check of unfolding method
• Remaining background spectrum is estimated using the sideband information, then the BG spectrum is subtracted from the spectrum obtained in the signal window.
• Raw distributions are corrected for detector responses by an unfolding process that is based on the iterative Bayesian method.(G. D’Agostini NIM A 362 (1995) 487)
• Detector response corrected spectrum is then corrected for acceptance
LHCf-Arm1√s=7TeV9.0<y<11.0
True EPOSUnfolded(by π0+EPOS)Unfolded(by π0+PYTHIA)
Measured EPOS
Acceptance and unfoldingSubmitted to PRD (arXiv:1205.4578).
π0 results: Data vs MC
π0 results: Data/MCSubmitted to PRD (arXiv:1205.4578).
Data/MC commented
dpmjet 3.04 & pythia 8.145 show overall agreement with LHCf data for 9.2<y<9.6 and pT <0.25 GeV/c, while the expected p0 production rates by both models exceed the LHCf data as pT becomes large
sibyll 2.1 predicts harder pion spectra than data, but the expected p0 yield is generally small
qgsjet II-03 predicts p0 spectra softer than LHCf data
epos 1.99 shows the best overall agreement with the LHCf data.
behaves softer in the low pT region, pT < 0.4GeV/c in 9.0<y<9.4 and pT <0.3GeV/c in 9.4<y<9.6
behaves harder in the large pT region.
<pT> distribution
Three different approaches used to derive the average transverse momentum, ⟨pT⟩1. by fitting an empirical function
to the pT spectra in each rapidity range (exponential distribution based on a thermodynamical approach)
2. By fitting a gaussian distribution
3. by simply numerically integrating the pT 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 <pT> on ECMS.
YBeam=6.5 for SPSYBeam=8.92 for7 TeV LHC
900 GeV inclusive g spectra
“Measurement of zero degree single photon energy spectra for √s = 900 GeV proton-proton collisions at LHC“PLB 715 (2012) 298CERN-PH-EP-2012-048
Comparison wrt MC Models at 900 GeV
small-η
= La
rge to
wer
big-η =Small tower
g analysis: Comparison btw 900 GeV and 7 TeV spectra
Coverage of the photon spectra in the plane Feynman-X vs PT
small-η
= La
rge to
wer
big-η =Small tower
A jump back to g analysis: Comparison btw 900GeV and 7TeV spectra
Coverage of the photon spectra in the plane Feynman-X vs PT
900GeV vs. 7TeVwith the same PT region
900 GeV Small+large tower
small-η
= La
rge to
wer
big-η =Small tower
A jump back to g analysis: Comparison btw 900GeV and 7TeV spectra
Normalized by the number of entries in XF > 0.1 No systematic error is considered in both collision
energies.
XF spectra : 900GeV data vs. 7TeV data
Good agreement of XF spectrum shape between 900 GeV and 7 TeV. weak dependence of <pT> on ECMS
Preliminary
Data 2010 at √s=900GeV(Normalized by the number of entries in XF > 0.1)Data 2010 at √s=7TeV (η>10.94)
Coverage of the photon spectra in the plane Feynman-X vs PT
900GeV vs. 7TeVwith the same PT region
900 GeV Small+large tower
Neutron and K0 (very preliminary…) analyses
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 Detection Efficiency and energy linearity
Efficiency at the offline shower triggerFlat efficiency >500GeV
%
Linear fitParabolic fit
Energy and Position Resolution
X Y
Neutron incident at (X,Y) = (8.5mm, 11.5mm) ~1mm position resolutionWeak dependence on incident energy
We are trying to improve the energy resolution by looking at the ‘electromagneticity’ of the event
K0 analysis
K0 Acceptance
Status of the LHCf preparation for 14 TeV
LHCf preparation for the 14 TeV p-p run
Calorimeter radiation hardening by replacing plastic scintillator with GSO Scintillator plates
3 mm 1mm thick scintillators Acrylic quartz light guides
construction and light yield uniformity test carried out in Japan SciFi
1 mm square fibers 1 mm GSO square bars No clad-core structure (GSO bar)
Attenuation and cross talk test carried out Acrylic light guide fiber quartz light guide fibers
Construction and light yield test carried out
Production and laboratory tests of the new scintillators in Japan is finished
Beam test at Ion facility (HIMAC) has been done in June 2012
Arm1 has been re-assembled in Florence starting from end of June
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
Beam test at the SPS
Long beam test has been conducted from August 17th to September 4th in the H2 SPS area Muons, 50-250 GeV electrons, 350 GeV protons More than 1 TB of data
Main goals: Energy scale of upgraded Arm1 detector Check of energy scale of not upgraded Arm2 for the p/Pb
run Test of the solution to improve the silicon saturation for
14 TeV run Check of the temperature dependence of the absolute
energy scale both for Arm1 and Arm2
Very successful beam test!
Test of new silicon pattern bonding
Problem: saturation of the silicon electronics for Eg > 1.5 TeV Pace3 dynamic range is not enough to sustain such
a huge energy release Not a problem for 3.5+3.5 TeV runs
Software corrections based on the different PACE3 samples allow to increase saturation up to 2.5/3 TeV
Become an issue for 7+7 TeV run We will change the silicon sensors position to improve
the silicon only energy resolution…. We developed a new idea to hardware improve the
saturation level
Silicon sensor
Not used
Normal configuration
New configuration
Readout
ReadoutFloating
Readout
ReadoutGround
Arm2 detector New silicon
Pb (40mm)
e-, 200 GeV/c
Different silicon bonding scheme
The beam test setup
80 mm implant pitch160 mm readout pitch
New Silicon Module results (Quick analysis)
Clearly the pulse height in the region of new configuration were reduced by a factor of 1.5 ~ 1.7 (we could naively expect 2)
The modification works fine to enlarge the silicon dynamic range
#Strip
Normal New
Silicon Lateral distribution
Histogram of peak values
Arm2 Pi0 Mass v.s. Temperature at LHC
15-Mar.-2012 /31-Mar-2012
Remember the 3.8% Mass Shift that was longly discussed….
Temperature test and control at SPS
During the beam test, we carefully controlled the temperature of the detector with a chiller
We waited for some hours until the temperature was very stable (< 0.1 degree / hour)
Chiller
Water
Temperature test (Arm2)
Check the temperature dependency of the energy scale by changing the chiller temperature to 18, 23, 28, 33 degrees.
18
23
28
33
Chiller temperature
Thermometer in Arm2
Energy scale temperature dependence(Arm2)
The temperature coefficient is consistent with the R7400U catalog value (-0.20% /C)
We could confirm that there is a dependence of energy scale on the temperature.Compatible with 3.8% mass shift???? To be checked
Re-installation for the p/Pb run
Arm2 will be re-installed in the TAN during the technical stop foreseen at the end of the p/p run
We have modified the LHCf support structure and cabling to significantly reduce the installation required time
The procedure for reinstallation has been carefully discussed in the LTEX meetings and is ready Checked with RP RP gave green light
We are continuing discussions with ATLAS for trigger and data exchange, to get the maximum physics outcome for the data, following the LHCC recommendation
Arm2 will be brought back to Florence after the p/Pb run completion (special transport will be necessary because of the slight radioactivity)
Miscellanea…. I
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 was under discussion… Please stand by a little bit to see how things are
evolving!!!!
We have a new Japanese expert post doc that will stay in Italy for 2 years paid by Japan
Miscellanea II:Working together with MC model developers
Since the first paper we are in strict connection with model developers (EPOS,QGSJET, SYBILL etc.) We have taken part to several meetings/workshops We are contributing to the tuning of the model to LHCf
data
We are also involved in the MCPLOTS/RIVET project (http://mcplots.cern.ch) a simple browsable repository of MC (Monte Carlo) plots
comparing High Energy Physics event generators to a wide variety of available experimental data, for tuning and reference purposes
Miscellanea III:Working together with other LHC MC contacts
Since last year we are involved in one of the WG of the MC4LHC project
A new WG is now starting to focus on astroparticle physics connection with contact persons from each LHC experiments A. Tricomi, T. Sako Set up and organize a workshop
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
quest’anno 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 107 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 l’acquisto delle CPU
Miscellanea V: Missioni estere
Ad Aprile 2012 la CSN1 ci aveva sbloccato 35 kE di Missioni Estere che erano SJ al run p/Pb
Dato che il run p/Pb è stato spostato al 2013, restituiamo alla CSN1 27 kE di ME (21 kE da Firenze e 6 kE da Catania) Cerchiamo di effettuare più lavori possibile nel 2012
Setup di control room e DAQ Test di interfaccia con la macchina Installazione meccanica nel tunnel
Con la ragionevole speranza che ci vengano riassegnati per il 2013!!!!!!
Conclusions
The analysis work is nicely going on Very important and tight contacts with the theorists and
the model developers to maximize the outcome of the LHCf results
Arm1 upgrade has been completed Arm2 is ready to be installed for the 2013 p/Pb run Very successful test beam has been completed in
summer 2012 Arm2 upgrade will be completed in 2013 Ready to take data at 14 TeV And…. Possible Light Ions runs at RHIC/LHC are under
investigation
Spares slides
Temperature dependency (Arm1)
The temperature dependency has been also checked for Arm1.The coefficient of GSO may be bigger than PMT, about - 0.5% / degree.Compared the histograms of dE in each layer at 18, 23, 28, 33 chiller temperatures.
T_Chiller
2318 28 33
Layer 03 Layer 04
Layer 06Layer 05
The coefficient is between 0.17% degree and 0.45% / degree.Slightly bigger than Arm2, but not so serious.
Fast install/uninstall
Silicon strip FE electronics
LHCf main detector
Calorimeters amplifier
To be assembled in a single structure
Now 35 BNC connections in the tunnel
To be packed in 2-3 Harting multipoles connectors
Now 3 main structures installed separately
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-1 @ 14TeV pp)
1 kGyNot irradiated ref. sample
Irradiated sample
τ~4.2h recovery
K. Kawade et al., JINST, 6, T09004, 2011
Dose rate=2 kGy/hour(≈1032cm-2s-1)
Global LHCf physics programLHCf measurement for p-Pb interactions at 3.5TeV proton energy could be easily and finely integrated in the LHCf global campaign.
Period TypeBeam energy
LAB proton Energy
(eV)
Detector
2009 p - p450+450
GeV 4.3 1014 Arm1+Arm2
2009/2010 p - p
3.5+3.5 TeV 2.6 1016 Arm1+Ar
m2
2013 p – Pb 3.5 TeV proton E
1016 Arm2
2014 p - p 7+7 TeV 1017
Arm1+Arm2
upgraded
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
Proton remnant side – Invariant cross section for isolated g-rays
What LHCf can measure in the p+Pb run (2)Study of the Nuclear Modification Factor
Nuclear Modification Factor measured at RHIC (production of p0): strong suppression for small pt at <>=4.
LHCf can extend the measurement at higher energy and for >8.4Very important for CR Physics
Phys. Rev. Lett. 97 (2006) 152302
Lead-remnant side – multiplicityPlease remind that EPOS does not consider Fermi motion and Nuclear Fragmentation
n
Small tower Big tower
Minimum required number of collision: Ncoll = 108 (factor 10 more statistics wrt shown plots) Integrated luminosity Lint = 50 mb-1
2106 single photons expected on p-remnant side
35000 0 expected on same side
Assuming a pessimistic scenario with luminosity L = 1026 cm-2s-1 : Minimum running time for physics t = 140 h
(6 days)
… and required statistics to complete the p/Pb physics run