for meson spectroscopy New detectors for meson spectroscopy in Hall B at JLab Baryons2013, June 27 2013 Gabriel Charles

Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 1 New detectors for meson spectroscopy in hall-B at Jefferson Lab 1) Meson spectroscopy at CLAS12 2) Feasibility 3) Detector development and time schedule De Marco : Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 1

Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 2 Why meson spectroscopy ? Meson spectroscopy at CLAS12 In the quark model, quantum numbers of mesons are constrained : Total angular momentum J : |L-S|<J<L+S Parity P = (−1) 𝐿+1 Charge conjugation C = (−1) 𝐿+𝑆 where L and S are respectively the orbital angular momentum and the spin States for L=0,1,2 Forbidden states ( 𝟎 −− , 𝟎 +− , 𝟏 −+ ...) are called exotic mesons. They can be glueballs, tetraquarks, a meson composed of two quarks and one gluon ... The discovery of one these states would give a strong proof of the existence of other quark-gluon configurations. The MesonEx collaboration has proposed to perform meson spectroscopy at CLAS12. Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 2

Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 3 Jefferson Lab, Newport News, Virginia Meson spectroscopy at CLAS12 About the Hall B : Started to take data in 1996 Around 160 collaborators in 12 countries from more than 40 different institutions Focused on understanding nucleon structure Hall A Hall B Hall C Main physics focus of the Hall B : What is the longitudinal and transverse structure of the hadron ? What is the 3D structure of the hadrons ? What is the hadronic spectra ? Hadrons and cold nuclear matter About the accelerator : Two linear accelerators connected by recirculation arcs Continuous electron beam Upgraded very soon to deliver a 12 GeV electron beam at a luminosity of 10 35 𝑐𝑚 −2 𝑠 −1 Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 3

Meson spectroscopy at CLAS12 Fixed target experiment 11 GeV continuous electron beam liquid hydrogen target 4𝜋 detectors good particule identification and energy resolution Spectropscopy will use quasi-real photons as a probe. Something different than pions for complementarity. For the moment kaons can be detected only by CLAS12, Hall D they have recently proposed something but it’s tricky. As 𝑄 2 = 4EE’ 𝑠𝑖𝑛 2 (θ/2), electron at low angles must be detected. new detectors at low angles are required Example of studied reactions Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 4

Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 5 Forward Tagger Meson spectroscopy at CLAS12 Electromagnetic calorimeter The Forward Tagger is 1.8 m away from the target. It aims to reconstruct the scattered electron between 2.5° and 4.5°. Hodoscope Micromegas tracker Three new detectors will be added to the Hall B : Electromagnetic calorimeter to reconstruct the energy of the electron Hodoscope to differenciate photons and electrons Micromegas tracker to determine the space variables of the electron The Forward Tagger has been implemented to Gemc and a full analysis performed. Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 5

Missing mass reconstruction Simulations Feasibility Full reconstruction of a 3𝜋 reaction with the software framework of CLAS12 has been performed. Acceptance Missing mass reconstruction Fast MC simulations Gemc Good agreement between fast Monte Carlo and realistic simulations Excellent differenciation of 3𝜋 from 4𝜋 events X mass resolution is around 10 MeV/c². + PWA to determine the quantum numbers Experiment has been approved with 118 days of beam time. Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 6

Detector developpment Calorimeter Detector developpment APD LED The main elements of the calorimeter are : a matrix of 332 crystals each crstal is made of 𝑃𝑏𝑊𝑂 4 and has a rectangular shape of 15 x 15 x 200 𝑐𝑚 3 cooling system APDs and pre-amplifiers amplifier crystal downstream peek support Momentum resolution from simulations Tooling for crystal assembly lead tungstate Resolution is about 3.5 % from 2 to 4.5 GeV/c and 2 % at 0.5 GeV/c Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 7

Photon misidentification Hodoscope Detector developpment The main elements of the hodoscope are : two layers of plastic scintillators (Eljen-204) to minimise photon mis-ID The first layer is 7 mm thick and the second 15 mm thick WLS fibers silicon PM Time resolution (from simulations) Photon misidentification (from simulations) Recent and on-going work : design of the fiber holder fiber protection fiber connector to the SiPM Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 8

Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 9 Micromegas tracker Detector developpment The main elements of the tracker are : two layers of two Micromegas detectors each detector has an internal radius of 67 mm and an external radius of 142 mm a dedicated electronics for the 3,600 channels signal cables of about 1 m Angular resolutions (from simulations) The detector is very similar to the Micromegas developped by the CEA Saclay for the Forward Micromegas Tracker (FMT). Prototypes for the FMT have already been succefully tested and a prototype for the Forward Tagger will be tested during the summer. Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 9

Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 10 Mechanical design Detector developpment 95 % Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 10

Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 11 Time schedule Detector developpment Installation maybe be delayed due to funding issues. Gabriel.Charles@cea.fr CEA Saclay Baryons2013, 06/27/2013 11