RHICf physics introduction UHECR interaction Yoshitaka Itow KMISTEL

RHICf physics introduction - UHECR interaction Yoshitaka Itow (KMI/STEL, Nagoya University) RHICf collaboration open meeting BNL , Jun 13, 2016 2014/06/12 RHIC PAC meeting 1

Motivation : cosmic ray interactions Air shower HEAT TALE Tibet. AS HAWC Knee 0. 2 0. 5 Cosmic rays 1014 0. 9 2. 2 AUGER, TA 2 nd Knee? 7 14 Te. V 1017 Ankle GZK Colliders 1020 e. V l Need dedicated very forward measurement at hadron c l So far LHCf measured pp (7, 2. 76, 0. 9 Te. V) and p-Pb(5 l RHIC data at the low end is important for extrapolation l RHIC can serve p-LI or LI-LI collisions ( LI: light ion, ex 2

① Inelastic cross section (TOTEM and others) ③ Inelasticity k= 1 -plead/pbeam (LHCf forward neutron, n / g ratio ) ④ Nuclear effect (shadowing, Cronin effect) Composition error #of particles ⑤ 2 ndary interactions (√s dependence ) ② Forward energy spectrum ( LHCf g /p 0 spectrum) Atm. depth SD E-scale error 3

UHECR interaction; Impact on chemical composition • • UHECR MC (EPOS, QGSJET II) tuned by LHC data now Shower max diff. improved ( 50 -> 20 gcm 2 ), c. f. 100 gcm 2 btw p - Fe Question is energy extrapolation from 1017 to 1020 e. V Do we understand even 1014 to 1017 e. V ? EPOS QGSJET- 0 g/cm 2 Xmax T. Pierog, S. Ostapchenko, ISVHECRI 2012 1017 1020 4

Figure by T. Pierog 2 ndary particle productions proton String fragmentation q h q LHCf Very forward central Projectile diffraction LHCf sees 5

The LHCf experiment LHCf Arm#1 Two independent detectors at either side of IP 1 (Arm#1, Arm#2 ) 140 m Beam pipe Charged particles (+) Beam 96 mm ATLAS Neutral particles LHCf Arm#2 Charged particles (-) • • All charged particles are swept by dipole magnet Neutral particles (photons and neutrons) arrive at LHCf 0 degree is covered ( 8. 6 < | h | < infinity ) Carried out at LHC 0. 9, 2. 76, 7, and 13 Te. V p+p and 5 Te. V p+Pb 6

The LHCf detectors Here we assume to use Arm 1 Arm 2 44 X 0, 1. 6 lint 16 tungsten + pl. scinti. layers 25 mmx 25 mm+32 mmx 32 mm 4 Silicon strip tracking layers 16 tungsten + pl. scinti. layers 20 mmx 20 mm+40 mmx 40 mm 4 Sci. Fi tracking layers 7

PID (SPS energy) EM shower (SPS) Hadronic shower (LHC MC) JINST, 9, P 03016 (2014) energy resolution (%) NIM, A 671 (2012) 129 -136 JINST, 5, P 01012, 2010 position resolution (mm) position resolution (μm) p 0 mass 8

h>10. 94 7 & 0. 9 Te. V pp photon PLB 703 (2011) 128 -134 PLB 715 (2012) 298 -303 h> 10. 76 7 Te. V pp neutron Submitted PLB LHCf results summary 7 Te. V pp p 0 PRD 86 (2012) 092001 5 Te. V p. Pb p 0 PRC 89 (2014) 065209 ary n i im l e r P

Feynman scaling : a key for extrapolation • Many models naturally include XF scaling violation • Important to extrapolate from LHC to GZK • Impact also on air shower structure； Xmax LHC single gamma data (900 Ge. V pp / 7 Te. V pp) p 0 Xf ’s from models (7 Te. V and 100 Te. V ratio to 0. 9 Te. V) Data Preliminary 0. 9 Te. V (h>8. 68) 7 Te. V scaled (h>10. 94) 10

Feynman scaling in p 0 production preliminary • LHCf π0 spectra at √s= 2. 76 and 7 Te. V (preliminary) • RHICf can add data at √s=510 Ge. V, p. T<1 Ge. V/c

Very forward neutron (leading baryon) inelasticity k = = E_inel/Etotal ~ (Etotal – E_lead)/Etot A. Adare, et al. , Phys. Rev. D, 88, 032006 (2013) K. Kawade Ph. D thesis (2014) Preliminary RHIC PHENIX (200 Ge. V), ISR (30. 6 -62. 7 Ge. V) LHCf 7 Te. V neutron (Arm 1 only) 0<PT<0. 11 x. F Ge. V/c 12

Rapidity vs Forward energy spectra (in LHCf) Gamma-rays @ √s=14 Te. V h= 7. 6 8. 0 40 7 h= 450 mrad 0 h=5. 99 h=6. 91 8. 4 = h h= 7 8. 310 mrad 7 . 7 h=8 h= 8. 7 h= ∞ θ [μrad] η 310 8. 7 0 ∞ Viewed from IP 1 (red: Arm 1, blue: Arm 2) Projected edge of beam pipe 13

RHICf site at Z=18 m (~ 140 m x 500 Ge. V/7 Te. V) h>5. 8 p RHICf 18 m RHICf calorimeter Existing ZDC IP Beam pipe Neut ral p artic les • Same Pt coverage as LHC 7 Te. V • RHICf+ZDC better neutron E and Pt resolution 14

RHICf expected distributions (1 hour; pos 1)

RHICf expected pi 0 (1 hour; pos 1)

Diffraction tagging with STAR and Roman pots (joint operation with STAR ) p RP STAR g, n single diffraction RHICf Diffractive mass ξ by RP No high p. T tack in central

Summary • RHICf : neutral measurement at RHIC zerodegree by LHCf Arm 1 detector. – high energy cosmic ray interactions at ~1014 e. V – Very forward production at zero degree • RHICf 500 Ge. V pp gives similar acceptance as LHC 7 Te. V. – Good verification of Feynman scaling in similar acceptance with the same detector. • Integration into STAR – ZDC : improved hadron energy reconstruction – Central detector+RP : diffractive tagging, event shape.

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PLB 703 (2011) 128 -134 LHCf single g spectra at 7 Te. V and 0. 9 Te. V PLB 715 (2012) 298 -303 h>10. 94 7 Te. V 8. 81<h<8. 99 0. 9 Te. V 3. 5 Te. V h>10. 15 DPMJET 3. 04 QGSJETII-03 SIBYLL 2. 1 EPOS 1. 99 PYTHIA 8. 145 3. 5 Te. V 8. 77 <h<9. 46 20

LHCf p 0 PT spectra at 7 Te. V PRD 86 (2012) 092001 Type-II 1

LHCf EM(p 0) energy flow vs rapidity (7 Te. V) Plot by N. Sakurai 22

Very forward neutron at 7 Te. V p-p • h>10. 76 : QGSJET 03 good, >h>9. 22 DPMJET 3 good • Larger neutron / gamma ratio than expected 40% E res. unfolded h> 10. 76 8. 99<h<9. 22 y r a n i m i l Pre Data 3. 05± 0. 19 Data 1. 26± 0. 08 DPMJET 3. 04 EPOS 1. 99 PYTHIA 8. 145 QGSJET II-03 SYBILL 2. 1 1. 05 1. 80 1. 27 2. 34 0. 88 DPMJET 3. 04 EPOS 1. 99 PYTHIA 8. 145 QGSJET II-03 SYBILL 2. 1 0. 76 0. 69 0. 82 0. 65 0. 57 n/g ratio n / g ratio ary n i im Prel 23

LHCf neutron energy flow vs rapidity Plot by N. Sakurai 24

Feynman scaling violation and air showers T. Wibig, Phys Lett B 678 (2009) 60 Air shower max for UHECR data a ; scaling violation parameter

√s scaling : a key for extrapolation beyond the LHC All π0 expected from models (0. 5 Te. V, 14 Te. V and 50 Te. V) LHCf single photon data (900 Ge. V pp , 7 Te. V pp) DPMJET 3 QGSJET II Preliminary 0. 9 Te. V (η>8. 68) 7 Te. V scaled (η>10. 94) Comparison done in the very limited phase space of 900 Ge. V co (green triangle in the phase space plot) 26

Event sample (π0 g 2γ ) at LHC 7 Te. V p+p Longitudinal development measured by scintillator layers 25 mm Tower 32 mm Tower 600 Ge. V 420 Ge. V photon Total Energy deposit Energy Shape PID Lateral distribution measured by silicon detectors Hit position, Multi-hit search. X-view Y-view π0 mass reconstruction from two photon. Systematic studies 27

Detector performance Ehad resolution Eg resolution 4% Number of event 100 200 Ge. V electrons 200 E(Ge. V) 350 Ge. V protons sx=172 mm Position resolution For hadron, Dx~2. 5 mm x-pos[mm] 28

Hadron shower reconstruction Check by SPS 350 Ge. V p beam 29

Xf ratio ( p 0 )