ifae 2012 / ferrarae. cisbani / experimental physics at jlab1 13 april 2012 ifae 2012 – ferrara...
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IFAE 2012 / Ferrara E. Cisbani / Experimental Physics at JLab 1
13 April 2012IFAE 2012 – Ferrara
Experimental Physics at JLab:where confinement meets asymptotic
freedomEvaristo Cisbani
INFN-Sanità and Istituto Superiore di Sanità
The Jefferson Laboratory and the Italian collaboration Physics (excerpt)
• Nucleon Structure (Form Factor and Quark Distribution)• Hadron Spectroscopy• Parity Violation Experiments
Technological Developments• HD Polarized Target• Photon Tagger• RICH/Clas12• GEM/SiD Trackers
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Thomas Jefferson National Laboratory
• Newport News / Virginia / USA (3 ore da Washington DC)
• DOE funding + Local Universities and Organizations
• Director: H. E. Montgomery (ex-associate director for research al Fermilab)
• 2000 International Users• Fundamental Research by electron
accelerator on 3+1 experimental Halls• Applied research by FEL and other facilities• Web site: www.jlab.org
more than
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CEBAF accelerator
AB
C
Lina
c
Linac
Arc
Arc
Injector
• Linear Recirculating e- Accelerator with
superconductive cavities• Polarized beam
• High current (200 mA)• Max. energy 6 GeV
• 100% duty factor• Beam released
simultaneously on three experimental Halls: A, B
and C
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Hall A Hall B/CLAS Hall C
Two High Momentum Resolution + one large angular acceptance spectrometers
Dedicated neutron and gamma detectors
Large acceptanceHigh multiplicity
reconstructionSix coils Toroidal
field
Two asymmetric spectrometers
High momentum range and high resolution
Dedicated detectors
High beam currents (>100 mA), lumi 1037
cm-2 s-1
Tagged real photons beam
High beam currents (>100 mA), lumi 1037
cm-2 s-1
3He T/L Polarized target, high flexibility unpol. from H to Pb
NH3/ND3 Polarized long. target
NH3/ND3 Polarized long. target, high flexibility unpol. from H to Pb
Large and flexible installations
4p coverage Moderately large and flexible installations
Current Experimental Halls
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CEBAF after 2013
CHL-2
Upgrade magnets and power supplies
add Hall D (and beam line)6 GeV CEBAF (< 2013)
Max Current: 200 mAMax Energy: 0.8 - 5.7 GeVLong. Polarization: 75-85%
12 GeV CEBAF
(>2013)Max Current: 90 mAMax Energy Hall A,B,C: 10.9 GeVMax Energy Hall D: 12 GeVLong. Polarization: 75-85%
$ 310M
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Hall A Hall B/CLAS12 Hall C Hall D/GLUEX
+ 1 large angular and momentum, high lumi spectrometer with hadron ID
+ Solid detector+ Möller detectorNew beam line
New ~2p toroid detector with extended hadron ID
+ “super high” momentum spectrometer
+ dedicated equipment
Excellent hermetic coverage,
Solenoid field
High multiplicity reconstruction
+ lumi 1038 cm-2 s-1 + forward tagger for quasi-real photons
108 linearly polarized <12 GeV
real photons/s
+ targets with large thickness
+ long/trans polarized H/D target
hallaweb.jlab.org www.jlab.org/Hall-B www.jlab.org/Hall-Cwww.jlab.org/Hall-D
www.gluex.org
Experimental Halls after 2014
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JLab physics
• Origin of quark and gluon confinement (B & D)
– Gluonic excitations - existence and properties of exotic mesons (and baryons)– Heavy baryon and meson spectroscopy
• Structure of the Hadrons (A,B and C)– Parton Distributions Functions (and Fragmentation Functions)– New view of nucleon structure via the Generalized Parton Distributions (GPDs)
accessed in Exclusive Reactions– Form Factors - improve knowledge of charge and current in the nucleons;
constraints on the GPDs– Quark propagation and hadron formation
• Dynamics of the nucleons in the nuclei (A, B and C)– The Quark Structure of Nuclei (resolving the EMC effect)– The Short-Range Behavior of the N-N Interaction and its QCD Basis– Cold nuclear matter
• Electroweak Interaction (A and C)– High Precision Tests of the Standard Model at low energies via Parity-Violating
Electron Scattering Experiments– Measure nuclear properties by weak interaction
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Sezioni INFN partecipanti (BA, CT, GE, FE, ISS, LNF, RM, RM2):Ricercatori + Tecnologi: ~ 50 (32.3 FTE)
Intensa attività sperimentale al JLab/6 GeV (prevalentemente in sala A e B)
Forte coinvolgimento negli sviluppi legati al raddoppio di energia del fascio e aggiornamento degli apparati nelle sale sperimentali
Esperimento INFN formalmente attivo
dal 2009 per 7 anni, nasce dalla
sinergia delle ex sigle AIACE + LEDA
per sfruttare al meglio le opportunità
sperimentali offerte
dall’aggiornamento a 12 GeV
new deputy per la fisica al JLab !Coordinatori Nazionali: E. Cisbani, P. Rossi
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Nucleon (Spin) Structure
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The “ultimate” description of the nucleon
3D view of the nucleonTransverse Momentum Dependent (TMD) parton distribution and fragmentation functions • Describe correlations between the transverse
momentum of quarks/gluons and spin• 3D picture of nucleon in momentum space
Generalized Parton Distribution functions (GPD) • Describe correlations between the transverse
coordinates of quarks and spin• 3D picture of nucleon in mixed momentum and
transverse spaceN
ucle
on
Quark
Information on: nucleon spin origin, quark orbital angular momentum,relativistic effects in QCD, quark/gluon Q2 evolution,
QCD gauge invariances ...
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11Adapted from P. Rossi, JLab 2012
TMD’s latest results at JLab
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First ‘direct’ measurement on neutron
n - Collins small, largely compatible to 0; Sivers negative (?) for p+, zero for p-
Collins Moment = h1 Collins FF Clean probe of relativistic effects
Sivers Asymmetry = f1T TMD Unpol. FF
Link to quark Orbital Angular Momentum
Experimental limits:Modest statistics, integrated on the relevant kinematical variables (x,z,pT),no access to large x, valence region, no clean interpretation of the data.
Adapted from A. Puckett, JLab 2011
D
F TMDs @ JLab 12 GeV
E12-09-018: p/kE12-10-006: p
3He
Hall A SBS/SOLID
HALL CHMS+SHMS
E12-09-017: /p kC12-11-102 p0
Hall BCLAS12
C12-11-111: /p k
H2, D2NH3HDH2, NH3, D2,
ND3
E12-06-112: pE12-09-008: k
E12-07-107: pE12-09-009: k
A Multi-Hall TMDs program
- Large variety of targets- Different species of detected hadrons
-High luminosity experiments- Extended phase space
Adapted from P. Rossi, JLab 2012
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E12-11-107: p
C12-11-108: p
Some TMDs projections
SOLID: e3He →e’p+/-X
E12-11-007
E12-09-009
CLAS12: e p →e’K+/-X longitudinally polarized target
6 GeV data
SBS: e3He →e’K+/- X(transverse target)
E12-09-018
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14Adapted from P. Rossi. JLab 2012
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Proton Form Factors
2tan
2
)( e
p
ebeam
l
t
Mp
Ep
M
EE
P
P
G
G
Polarization transfer from the incident electron to the scattered proton
22MpEp GG
d
d
Rosenbluth Separation: assume single photon approximation
Prior to JLab, expectations were that Gep/GMp was fairly constant with Q2
New focus on nucleon structure and description of elastis scattering (two photon exchange); possible role of quark OAM
e + p → e’ + p’
e→ + p → e’ + p →’
At JLab, new class of experiments show GE/GMp decreasing linearly with Q2
Extended measurements of p/n form
factors at high Q2
Test different models (including
different contributions from the quark
OAM)
Investigate the transition region
(perturbative / non perturbative)
Constraint the H and E GPDs
Electromagnetic Nucleon Form Factors @12GeVE-12-07-109: Polarization transfer E-12-09-016: Double polarization
E-12-09-019: Cross section ratio
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Confinement Mechanism
(hadronization and spectroscopy)
Hadronization of quarks
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H. Matevosyan et al., Phys. Rev. D85 (2012) 014021
Transverse momentum distributions in hadronization may be flavor dependent
Employ nuclei as analyzers of
hadronization processes, to probe:
- The hadronization formation length
(0-10 fm)
- The time scale on which a qq pair
becomes dressed with its own
gluonic field
Study the SIDIS reaction on nuclei;
observables:
- The hadronic multiplicity ratio
- The transverse momentum
broadeningAdapted from P. Rossi, JLab 2012 E12-06-117
How hadrons form inscattering processes ?
Beyond the quark model: hybrids and exotics
mesons
Quarks are confined inside colorless hadronsthey combine to 'neutralize' color force
baryons
Other quark-gluon configuration can give colorless objects
QCD does not prohibit such states but not yet unambiguously observed
q qq
molecules glueball mesons hybrid mesonspentaquarks
q
qqq
q
q
q q
qqq
Adapted from M. Battaglieri, Genova 2012
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Hybrid mesons and glueballs mass range
1.4 – 3.0 GeV
Lattice-QCD predictions for the lowest exotics states:
0+- 1.9 GeV1-+ 1.6 GeV
This mass range is accessible in photoproduction experiments with a beam energy in the range 5 GeV < Eg <12 GeV
Perfectly matched to JLab12 energy!
QCD Lattice calculations
Exotics
ρ
Standard mesons
J.Dudek et al Phys.Rev.D82 (2010) 034508
Adapted from M. Battaglieri, Genova 2012
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Unambiguous experimental signature for the presence of gluonic degrees of freedom in the spectrum of mesonic states
S=S1+S2 J= L+S P = (-1) L+1 C= (-1) L+S
Combine excited glue quantum number with those of the quarks
Normal meson:flux tube in ground statem=0CP=(-1) S+1
Hybrid meson:flux tube in excited statem=1CP=(-1) S
Flux tube JPC 1-+ , 1+-
Search for mesons with 'exotic' quantum numbers(not compatible with quark-model)
Not-allowed: JPC = 0-- , 0+- , 1-+ , 2+- ...
Meson spectroscopy with photons at JLab
Adapted from M. Battaglieri, Genova 2012
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Hall-D - GlueX Detector Hall-B - CLAS12 Detector
Meson spectroscopy with photons at JLab-12 GeV
• Good resolution• Good pID• Reasonable hermeticity• Un-uniform acceptance
• Good hermeticity• Uniform acceptance• Limited resolution• Limited pID
Forward Tagger
• Determination of JPC of meson states requires PWA• Decay and production of exclusive reactions• Good acceptance, energy resolution, particle identification
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22Adapted from M. Battaglieri, Genova 2012
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PVES(parity violating electron scattering)
0Z
e e
+
2
Esperimenti di Violazione della Parità• Misura accurata della asimmetria nei processi elastici (e DIS) di elettroni
polarizzati longitudinalmente su nucleone/nucleo non polarizzato
• Accesso alle costanti di accoppiamento deboli elettroni-quark (u/d) delle correnti neutre, ovvero alla corrente debole del protone, ovvero all’angolo di mixing debole
• Pone limiti su esistenza di nuova fisica (PVDIS, QWeak, Möller) • Ha permesso la misura del contributo dei quark s ai fattori di forma del
nucleone (HAPPEX, G0)• Permette la misura di importanti grandezze nucleari soppressi nei
processi elettromagnetici PREX
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Lead (208Pb) Radius Experiment: PREX
Z0 is a clean probe that couples mainly to neutrons
E = 850 MeV, J=6° electrons on lead
Elastic Scattering Parity Violating Asymmetry
~ 0.5 ppm
)(0130.0)(0604.0
6571.0
syststat
ppm
Statistics limited (9%)
Systematic error 2%!
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Measure of the radius of the neutron distribution in Pb
Relevant to astrophysics model contraints
Adapted from G.M. Urciuoli, Roma 2012
A neutron skin established at ~93 % CL
Neutron Skin = RN - RP = 0.33 + 0.16 - 0.18 fm
Neutron Radius = RN = 5.78 + 0.15 - 0.17 fm
Pins down the symmetry energy (1 parameter)
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26Adapted from G.M. Urciuoli, Roma 2012
First direct measurement
of the neutron skin
PREX-II Approved by PAC (Aug 2011)
“A” Rating 35 days run in 2013 / 2014
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27Adapted from G.M. Urciuoli, Genova 2012
Standard Model Test at low energy
Parity Violation Physics to test the SM at low energy: require high luminosity and
precise control of the systematics
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Accuracy projection
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JLab12
12 GeV era / Equipment
• HD Target,
• Forward Tagger,
• RICH,
• High Lumi Tracker
HD-ice: polarized frozen spin HD targetPolarized target of high dilution factor, made of solid Deuterium-Hydride:Longitudinal and Transverse Polarizations: up to 75% H and 40% DRelaxation time: > 1 year Polarization procedure » 3 monthsData taking: » monthsWide acceptance
Target cellTarget cell
Comparison of signal over background ratio:HD versus conventional polarized target
INFN contribution:• Dilution Refrigerator• Contribution to the construction of the new In-
Beam Dilution Refrigerator Cryostat• Raman analysis of ortho-hydrogen and para-
deuterium contents in HD gas• Magnetic Vari-Temp Cryostat for HD
condensation and NMR polarization measurements
Target Transfer Target Transfer
In-beam cryostat
Run with polarized deuterons from HD-ice & circularly polarized photons started on Dec. 2011: D polarization 27%
Run with polarized deuterons from HD-ice & linearly polarized photons started on April 2012: D polarization 30%
Test of HD-ice & electron beam performed in February: on-going analysis
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30Adapted from A. D’Angelo, Roma 2012
The Forward Tagger for CLAS12
31
New system to detect electrons at small angle and perform quasi-real photo-production experiments
Calorimeter
electron energy/momentumPhoton energy (ν=E-E')Polarization ε-1 ≈1 + ν2/2EE’PbWO4 crystals with APD/SiPM readout
Scintillation Hodoscope
veto for photonsScintillator tiles with WLS readout,…
Tracker
electron anglesPolarization scattering planeMicroMegas detectors
Moller Shield
Calorimeter
Tracker
Scintillation Hodoscope
HTCC Moller cup
GEMC implementation
e-
g*
CLAS12
p
e-
ForwardTagger
Adapted from M. Battaglieri, Genova 2012
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CLAS12 PID
RICH
GeV/c 1 2 3 4 5 6 7 8 9 10
p/K
p/p
K/p
e/p
HTCC
TOF
TOF
TOF
HTCC
HTCC
HTCCEC/PCAL
LTCC
RIC
HRIC
H
LTCCRICH
LTCCLTCCRICH
LTCCRICH
4-5 s p/K separation @ 8 GeV/c
Aerogel mandatory to separate hadrons in the 2-8 GeV/c momentum range collection of visible Cherenkov light use of PMTs
Challenging project, crucial to minimize Detector area
Option under investigation: proximity focusing RICH + mirrors
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32Adapted from P. Rossi, JLab 2012
AerogelElliptical mirrors
Photo-detectors
+ Planarmirrors
Proximity Focusing RICH + Mirrors
RICH Conceptual Design
Goal: reduce the photon detection area of MA-PMTs H8500 to ~ 1m2/sector
Elliptical and planar mirrors to focus the Cherenkov light of particles emitted at angles J > 12°
10 H8500
8 R8900
- Test with hadron beam at CERN with a prelininary RICH prototype (summer 2011)
number of Np.e obtained for direct ring in consistent with simulations- Test with electron beam at LNF (july 2012)- test of full prototype with p/K beam at CERN (august 2012)
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33Adapted from P. Rossi, JLab 2012
UvaJLabINFNRutgers U.College WMU. of GlasgowNorfolk State U.Carnegie Mellon U.U. of New Hampshire
SBS Spectrometer in Hall A
SiD
High luminosity ~1039/s/cm2
Moderate acceptance
Forward angles
Reconfigurable detectors
High luminosity ~1039/s/cm2
Moderate acceptance
Forward angles
Reconfigurable detectors
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40x150 cm2 GEM Tracker70 mm spatial resolution
High photons up to 250 MHz/cm2 and electrons 160 kHz/cm2 background
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QCD and confinement
Large DistanceLow Energy
Small DistanceHigh Energy
Perturbative QCDDIS ScatteringParton models
Strong QCDSpectroscopy
Phenomenological Models
s ~ QED QCDHigh luminosityPolarization (initial and final states)High beam stabilityComplementary EquipmentsDedicated, optimized detectors
JLaboffers
+ Test Standard Model
+ Dark matter search
www.iss.infn.it/webg3/cebaf