A Fixed-Target ExpeRiment (AFTER) using the LHC beams Cynthia Hadjidakis Annual meeting of the GDR PH-QCD Orsay, December 7 th 2012 1 Cynthia Hadjidakis Orsay December 7 th 2012
Overview • Beam extraction technique using bent crystal and its application at the LHC • Expected luminosities and physics opportunities for a fixed target experiment at the LHC • Expected yields for quarkonium production studies 2 Cynthia Hadjidakis Orsay December 7 th 2012
Strong crystalline fields in bent crystals Strong electric fields in the lattice nuclei of a crystal in the rest frame of the crossing particles In a bent crystal, guidance of particles ⇔ bending strength as for a magnetic dipole Many experiments for proton beam extraction and collimation using crystals: • RD22 @ CERN-SPS (1990-95) • E853 @ FNAL-Tevatron (1993-97) • INTAS @ U70 IHEP (2001-03) • RHIC (2001-05) • Tevatron (2005-11) • UA9 @ SPS (2008-...) • ... 3 Cynthia Hadjidakis Orsay December 7 th 2012
Strong crystalline fields in bent crystals Strong electric fields in the lattice nuclei of a crystal in the rest frame of the crossing particles In a bent crystal, guidance of particles ⇔ bending strength as for a magnetic dipole A. Baurichter et al., NIMB 164, 27 (2000) Many experiments for proton beam extraction and collimation using crystals: • RD22 @ CERN-SPS (1990-95) • E853 @ FNAL-Tevatron (1993-97) • INTAS @ U70 IHEP (2001-03) • RHIC (2001-05) • Tevatron (2005-11) • UA9 @ SPS (2008-...) • ... 3 Cynthia Hadjidakis Orsay December 7 th 2012
Next: beam collimation experiment @ LHC W. Scandale et al., JINST 6 T10002 (2011) BLM BLM Gonio Absorber Micro RP • LHC Committee approved beam bending experiments using crystals at the LHC (LUA9 Collaboration) • Beam collimation @ LHC: amorphous collimator: inefficiency @ 3.5 TeV proton beam = 0.2% → expected bent crystal inefficiency = 0.02% • Tests at SPS in 2012 on proton and ion beams for a LHC setup • Long Shutdown 1 (2013): bent crystals in LHC beams 4 Cynthia Hadjidakis Orsay December 7 th 2012
Next: beam collimation experiment @ LHC W. Scandale et al., JINST 6 T10002 (2011) BLM BLM Gonio Absorber Micro RP • LHC Committee approved beam bending experiments using crystals at the LHC (LUA9 Collaboration) • Beam collimation @ LHC: amorphous collimator: inefficiency @ 3.5 TeV proton beam = 0.2% → expected bent crystal inefficiency = 0.02% • Tests at SPS in 2012 on proton and ion beams for a LHC setup • Long Shutdown 1 (2013): bent crystals in LHC beams 4 Cynthia Hadjidakis Orsay December 7 th 2012
Next: beam extraction experiment at the LHC E. Uggerhoj and U.I Uggerhoj NIMB 234 (2005) 34 Continuous extraction in the beam dump line • Proton beam extraction • Proposal for the insertion of a bent - Single- or multi pass extraction efficiency of 50% - N beam loss LHC ~ 10 9 p/s → N extracted beam = 5 10 8 p/s crystal in the LHC beam - Extremely small emittance: beam size in the extraction - Bent, single crystal of Si or Ge - 17cm long direction) 950 m after the extraction ~ 0.3 mm crystal - MKD kicker section at ~200 m from IP6 - Deflection angle = 0.257 mrad (~7 T.m • Ion beam extraction equivalent magnet) - Ions extraction tested at SPS, is expected to be also - Distance of 7 σ to the beam to intercept and possible at LHC but needs more study deflect the beam halo - May require bent diamonds (highly resistant to - No loss in the LHC beam radiations) P. Ballin et al, NIMB 267 (2009) 2952 5 Cynthia Hadjidakis Orsay December 7 th 2012
Next: beam extraction experiment at the LHC E. Uggerhoj and U.I Uggerhoj NIMB 234 (2005) 34 Continuous extraction in the beam dump line • Proton beam extraction • Proposal for the insertion of a bent - Single- or multi pass extraction efficiency of 50% - N beam loss LHC ~ 10 9 p/s → N extracted beam = 5 10 8 p/s crystal in the LHC beam • Use LHC beams on fixed target - Extremely small emittance: beam size in the extraction - Bent, single crystal of Si or Ge - 17cm long – 7 TeV proton beam ( √ s ~115 GeV) direction) 950 m after the extraction ~ 0.3 mm crystal • p+H, p+A - MKD kicker section at ~200 m from IP6 - Deflection angle = 0.257 mrad (~7 T.m – 2.76 TeV Pb beam ( √ s NN ~72 GeV) • Ion beam extraction equivalent magnet) • Pb+A, Pb+H - Ions extraction tested at SPS, is expected to be also - Distance of 7 σ to the beam to intercept and possible at LHC but needs more study deflect the beam halo - May require bent diamonds (highly resistant to - No loss in the LHC beam radiations) P. Ballin et al, NIMB 267 (2009) 2952 5 Cynthia Hadjidakis Orsay December 7 th 2012
Luminosities in pH and pA @ 115 GeV • Intensity: N beam = 5.10 8 protons.s -1 • Instantaneous Luminosity L = N beam x N Target = N beam x ( ρ x e x N A )/ A – Beam: 2808 bunches of 1.15x10 11 p = 3.2x10 14 p – Bunch: Each bunch passes IP at the rate: ~11 kHz – N beam =5 x 10 8 p + /s – Instantaneous extraction: IP sees 2808 x 11000~3.10 7 – e (target thickness) = 1 cm bunches passing every second → extract ~16 protons in each bunch at each pass • Integrated luminosity – Integrated extraction: Over a 10h run: extract ~5.6% of – 9 months running/year the protons stored in the beam – 1 year ~ 10 7 s ⇒ Large luminosity in pH(A) ranging from 0.1 and 0.6 fb -1 for a 1 cm thick target ⇒ Larger luminosity with 50 cm or 1 m H2 or D2 target (1 m ↔ 20 /fb/yr = LHC in 2012) 6 Cynthia Hadjidakis Orsay December 7 th 2012
Luminosities in PbA @ 72 GeV • Instantaneous Luminosity • Intensity: N beam = 2.10 5 Pb.s -1 L = N beam x N Target = N beam x ( ρ x e x N A )/ A – Beam: 592 bunches of 7x10 7 ions = 4.1x10 10 ions – N beam =2 x 10 5 Pb/s – Bunch: Each bunch passes IP at the rate ~ 11 kHz – e (target thickness) = 1 cm – Instantaneous extraction: IP sees 592 x 11000~6.5.10 6 bunches passing every second → extract ~0.03 ions in • Integrated luminosity each bunch at each pass – 1 months running/year – Integrated extraction: Over a 10h run: extract ~15% of – 1 year ~ 10 6 s the ions stored in the beam ⇒ AFTER provides a large luminosity to study QGP related measurements 7 Cynthia Hadjidakis Orsay December 7 th 2012
Polarizing the hydrogen target • Instantaneous Luminosity L = N beam x N Target = N beam x ( ρ x e x N A )/ A x p ↑ range corresponds to Drell-Yan measurements – N beam =5 x 10 8 p + /s – e (target thickness) = 50 cm ⇒ AFTER provides a competitive uminosity to study target spin related measurements ⇒ Complementary x p range with other spin physics experiments 8 Cynthia Hadjidakis Orsay December 7 th 2012
Rapidity boost in a fixed target mode • Very high boost: projectile – With 7 TeV beam γ = √ s/(2m p ) = 61.1 and y CMS = 4.8 target – With 2.76 TeV beam x 1 x 2 γ = 38.3 and y CMS = 4.3 • y lab = y CM + y CMS For a 2 → 1 process (e.g. gg → QQbar) forward region: y CM >0 backward region: y CM <0 x 1,2 = M/ √ s e ±yCM • η = - ln tan θ /2 (= y for massless particles) y CM : QQbar CMS rapidity – With 7 TeV beam M : QQbar mass y CM = 0 ↔ θ ~ 16 mrad (0.9°) • y lab = 4.8 ↔ y CM = 0 → x 1 = x 2 • backward region: y CM < 0 → x 1 < x 2 • y lab (J/ Ψ ) ~ 1.2 → x 2 = 1 • y lab ( Υ ) ~ 2.4 → x 2 = 1 Good condition to access large target x 2 and low x F =x 1 -x 2 → -1: target-rapidity region 9 Cynthia Hadjidakis Orsay December 7 th 2012
Physics opportunities of A Fixed-Target ExpeRiment (AFTER) @LHC Idea: use LHC beams on fixed target • – 7 TeV proton beam ( √ s ~115 GeV) • p+H, p+A – 2.76 TeV Pb beam ( √ s NN ~72 GeV) • Pb+A, Pb+H Phys. Rep. (2012), 10.1016 • High boost and luminosity giving access to – QCD at large x – nPDF and nuclear shadowing – Spin physics using polarized target – W/Z production near threshold – Quark Gluon Plasma – Other ? • Multi-purpose experiment 10 Cynthia Hadjidakis Orsay December 7 th 2012
Gluon distribution at large x Gluon distribution function in the proton: very large uncertainty at large x also at large Q Unknown for the neutron Large uncertainty in nuclei at large x (LHeC will probe the low x ) 11 Cynthia Hadjidakis Orsay December 7 th 2012
Gluon distribution at large x Gluon distribution function in the proton: very large uncertainty at large x also at large Q Unknown for the neutron Large uncertainty in nuclei at large x (LHeC will probe the low x ) 11 Cynthia Hadjidakis Orsay December 7 th 2012
Gluon distribution at large x LHeC CDR J. Phys. G 39 (2012) 075001 Gluon distribution function in the proton: very large uncertainty at large x also at large Q Unknown for the neutron Large uncertainty in nuclei at large x (LHeC will probe the low x ) 11 Cynthia Hadjidakis Orsay December 7 th 2012
Gluon distribution at large x LHeC CDR J. Phys. G 39 (2012) 075001 Gluon distribution function in the proton: very large uncertainty at large x also at large Q Unknown for the neutron Large uncertainty in nuclei at large x (LHeC will probe the low x ) • Experimental probes @ AFTER – Quarkonia – Isolated photons – High p T jets (p T > 20 GeV/c) → to access target x g = 0.3 - 1 (>1 Fermi motion in nucleus) • Target versatility – Hydrogen – Deuteron (neutron) – Nuclei 11 Cynthia Hadjidakis Orsay December 7 th 2012
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