Samples of Hall B Results with Strong Italian Impact Hadron Spectroscopy Structure of the Nucleon Transition between Hadronic and Partonic Degrees of Freedom 11/11/2018 INFN visit at JLab

Hadron spectroscopy in CLAS and CLAS12 Hunting for new configurations beyond qq and qqq Quantitative understanding of quark and gluon confinement Revealing the nature of the mass of the hadrons See the QCD degrees of freedom at work accessing gluonic degrees of freedom Validate lattice-QCD predictions Photoproduction experiments with high statistics and high precision with CLAS@6GeV showed the discovery potential of Jefferson Lab First observation of the f0(980) in a photoproduction experiment f0(980) Meson Spectroscopy Program with CLAS12 Study the meson spectrum in the 1-3 GeV mass range to study qq interaction and identify gluonic excitation of mesons (hybrids) with 'exotic' quantum numbers Study strangeness-rich mesons exploiting the unique combination of particle Id and resolution of the CLAS12 detector Launch a new program to strengthen the role of JLab in hadron spectroscopy

The Forward Tagging Facility for CLAS12: Quasi-real electroproduction at Low Q2 A tagged photon beam will open new possibility for high quality physics beyond the already approved program Exotic meson search Hadron spectroscopy J/y threshold production ... Electron scattering at “0” degrees (2° - 5°)  low Q2 virtual photon  real photon Photon tagged by detecting the scattered electron at low angles Quasi-real photons are linearly polarized  Polarization ~ 65% - 20% High Equivalent Luminosity  Ng ~ 5 x107 g/s (unique opportunity to run thin gas target!) Calorimeter + Tracking Veto Electron energy/momentum Photon energy (n=E-E') Polarization e-1 ~ 1 + n2/2EE' Electron angles Q2= 4 E E' sin2J/2 j polarization plane To separate photons from electrons and to define the trigger Complementary to Hall-D (GLUEX) Exploits the unique PID & resolution of CLAS12 Institutions: Edinburgh U., Glasgow U., INFN (project coordination), JLab, NSU, Orsay, Saclay

Experimental Equipment for Hall B Polarized Target for electron beam ~700K$ Cerenkov Counter for low-Q2 ~300K$ Important contributions to base equipment and specific apparatus Large Angle Calorimeter for detection of neutrals ~4M$ Upgrade of the Bonus Electronics ~45K$ HD target fridge ~500K$ Start Counter for photon beam ~47K$ Tagger Electronics Upgrade ~70K$