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N ew detectors for meson spectroscopy in Hall B at JLab. Baryons2013, June 27 2013. Gabriel Charles. New detectors for meson spectroscopy in hall-B at Jefferson Lab . 1) Meson spectroscopy at CLAS12 2) Feasibility 3) Detector development and time schedule. - PowerPoint PPT Presentation
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New detectors for meson spectroscopy
in Hall B at JLab
Gabriel Charles
Baryons2013, June 27 2013
New detectors for meson spectroscopy in hall-B at Jefferson Lab
1) Meson spectroscopy at CLAS12
2) Feasibility
3) Detector development and time schedule
[email protected] CEA Saclay Baryons2013, 06/27/2013 1
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 = Charge conjugation C = where L and S are respectively the orbital angular momentum and the spin
States for L=0,1,2
Forbidden states (, ...) 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.
[email protected] CEA Saclay Baryons2013, 06/27/2013 2
Jefferson Lab, Newport News, Virginia Meson spectroscopy at CLAS12
Hall A
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
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 CHall 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
[email protected] CEA Saclay Baryons2013, 06/27/2013 3
Main physics focus of the Hall B :
CLAS12 Meson spectroscopy at CLAS12
• Fixed target experiment 11 GeV continuous electron beam liquid hydrogen target• 4 detectors• good particule identification and energy
resolution
Spectropscopy will use quasi-real photons as a probe.
As = 4EE’(θ/2), electron at low angles must be detected.
new detectors at low angles are required
[email protected] CEA Saclay Baryons2013, 06/27/2013 4
Example of studied reactions
Forward Tagger Meson spectroscopy at CLAS12
Electromagnetic calorimeterHodoscope
Micromegas tracker
• 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 is 1.8 m away from the target. It aims to reconstruct the scattered electron between 2.5° and 4.5°.
Three new detectors will be added to the Hall B :
The Forward Tagger has been implemented to Gemc and a full analysis performed.
[email protected] CEA Saclay Baryons2013, 06/27/2013 5
Simulations Feasibility
Fast MC simulations
Gemc
Missing mass reconstruction
+ PWA to determine the quantum numbers
Excellent differenciation of 3 from 4 events
X mass resolution is around 10 MeV/c².
Experiment has been approved with 118 days of beam time.
Acceptance
Full reconstruction of a 3 reaction with the software framework of CLAS12 has been performed.
Good agreement between fast Monte Carlo and realistic simulations
[email protected] CEA Saclay Baryons2013, 06/27/2013 6
Calorimeter Detector developpment
Momentum resolution from simulations
Resolution is about 3.5 % from 2 to 4.5 GeV/c and 2 % at 0.5 GeV/c
The main elements of the calorimeter are :• a matrix of 332 crystals• each crstal is made of and has a
rectangular shape of 15 x 15 x 200 • cooling system• APDs and pre-amplifiers
amplifier
APD
crystaldownstream peek support
LED
Tooling for crystal assembly
[email protected] CEA Saclay Baryons2013, 06/27/2013 7
Hodoscope
[email protected] CEA Saclay Baryons2013, 06/27/2013 8
Detector developpment
Time resolution (from simulations)
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
Recent and on-going work :• design of the
fiber holder• fiber
protection• fiber
connector to the SiPM
Photon misidentification(from simulations)
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
[email protected] CEA Saclay Baryons2013, 06/27/2013 9
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.
