* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download CLAS12 - Jefferson Lab
Magnetic stripe card wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Lorentz force wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Electromotive force wikipedia , lookup
Magnetometer wikipedia , lookup
Magnetic monopole wikipedia , lookup
Superconducting magnet wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Electromagnetism wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Force between magnets wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetoreception wikipedia , lookup
Electromagnetic field wikipedia , lookup
Magnetotellurics wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Electromagnet wikipedia , lookup
History of geomagnetism wikipedia , lookup
CLAS12 Drift Chambers Simulation and Event Reconstruction Latifa Elouadrhiri Jefferson Lab Hall B 12 GeV Upgrade Drift Chamber Review Jefferson Lab March 6- 8, 2007 Outline • CLAS12 Drift Chambers Requirements • Luminosity Studies: – Two methods: occupancy estimation, direct track reconstruction – Results: comparison of different methods • Resolution: p, θ, φ – Two methods: linearized calculations, track simulation and reconstruction – Results: comparison of different methods • Monte Carlo Simulation of Physics Reactions CLAS12 Drift Chambers Requirements Goals: Specifications: measure virtual photon flux accurately dq ~ 1 mrad dp/p < 1% select an exclusive reaction; e.g. only one missing pion dp < 0.05 GeV/c dq p < 0.02 GeV/c sinq df p < 0.02 GeV/c measure small cross-sections L = 1035/cm2/s layer occupancy < 4% Tracking efficiency>95% good acceptance at forward angles Df ~ 50% at q=5o R3 R2 R1 Arrangement of drift chambers in CLAS12 Background Situation at L=1033cm-2s-1, DT = 150ns Electrons Drift ChambersR1 Photons No Magnetic Field Background Situation at L=1035cm-2s-1, DT = 150ns Electrons Photons No Magnetic Field CLAS12 – Single sector (exploded view) CLAS 12 Solenoid provides magnetic field for guiding Møller electrons away from detectors. Beamline equipment CLAS12 Solenoid Requirements Provide magnetic field for charged particle tracking for CLAS12 in the polar angle range from 40o to 135o. Provide magnetic field for guiding Møller electrons away from detectors. Allow operation of longitudinally polarized target at magnetic fields of up to 5 Tesla, with field in-homogeneity of ΔB/B < 10-4 in cylinder of 5cm x 3cm. Provide full coverage in azimuth for tracking. Sufficient space for particle identification through time-of-flight measurements. CLAS12 Solenoid Minimize the stray field at the PMTs of the Cerenkov Counter Minimize the forces created by one magnet on the other CLAS12 Solenoid Requirements CLAS 12 Solenoid provides magnetic field for guiding Møller electrons away from detectors. Background Situation at L=1035cm-2s-1, DT = 150ns Electrons Photons No Magnetic Field Background Situation at L=1035cm-2s-1, DT = 150ns Electrons Photons One Event with 5 T Magnetic Field Møller Electrons in 5 Tesla Solenoid Field Distance from the beam line in (cm) Low Energy Moeller Electrons 0 20 40 60 80 z(cm) Møller Electrons in 5 Tesla Solenoid Field Distance from the beam line in (cm) Mid-Energy Moeller Electrons 0 20 40 60 80 z(cm) Møller Electrons in 5 Tesla Solenoid Field Distance from the beam line in (cm) High Energy Moeller Electrons Møller Shield 0 20 40 60 80 z(cm) Background Situation at L=1035cm-2s-1, DT = 150ns Electrons Photons One Event with 5T Magnetic Field Background Situation at L=1035cm-2s-1, DT = 150ns Electrons Photons One Event Shielding with 5 T Magnetic Field and Shielding Background Event Generator The Event generator code DINREG: Monte Carlo nuclear fragmentation event generator, reproduces multiplicities and spectra of secondary hadrons and nuclear fragments in electro- and photonuclear reactions. Generates events fully conserving 4-momentum, baryon number and charge in the reaction. Modified to include the electroproduction processes in the energy range 2 - 10 GeV. Has been used extensively at JLab for background and shielding calculations. CLAS12 Tracking Efficiency CLAS12 Tracking Efficiency High tracking efficiency at L = 1035 CLAS12- DC Geant Simulation • Geant Simulation: DC R3 – CLAS12 DC geometry – magnetic fields – Møller shield • Upgrade of the event reconstruction code Beamline Shielding • Luminosity Studies – Tracking efficiency – DC occupancy • Resolutions – P, q, f Solenoid Field DC R2 DC R1 CLAS12 Y(cm) TORUS - Magnetic Field Y Z X (cm) 3m CLAS12 Solenoid-Torus Magnetic Field Θ = 5o Solenoid B(Gauss) B(Gauss) Field in TORUS sector mid-plane 15o 10o Torus 30o B(Gauss) 20o B(Gauss) B(Gauss) Z(cm) 40o CLAS12 Single Event Display Low momentum track 5 degree angle particle Simulations of tracking resolutions • Use two methods: “MOMRES” and “RECSIS12” – MOMRES is a calculation of the change to p, q and x due to multiple scattering at fixed locations and due to finite spatial resolution • “linearized approach” - assumes small deviations from ideal • applies to “bend plane” variables only – RECSIS12 is the name of the CLAS tracking program, upgraded with the correct CLAS12 DC geometry • “clusters” found, left-right ambiguities in drift cells resolved locally, track segments from all super-layers are linked • final track is fit globally CLAS12 Momentum Resolution CLAS12 Angular Resolution CLAS12 Drift Chambers Resolution: Summary Momentum Resolution DP/P 35o 30o o 25 20o DQ(mrad) Angular Resolution 15o 10o 5o P resolution < 1% q resolution < 1mrad X resolution < 200 mm Dx(mm) Position Resolution CLAS12 Missing Mass Resolution CLAS12 Missing Mass Techniques ep → eL(pp-)X K K*(892) Summary • Drift Chamber system design parameters for the CLAS12 detector are well defined. They were developed based on: – extensive detector simulation in realistic background environment – direct track reconstruction in both solenoid and Torus magnetic fields – extensive simulation of the physics processes of the 12 GeV science program • The current design of the Drift Chambers in combination of the Torus and solenoid design will allow us to operate CLAS12 with L ≥ 1035 cm-2s-1 and achieve excellent resolution in p, q and f. • With these capabilities the CLAS12 will be able to carry out a world-class experimental program in fundamental nuclear physics. Summary The magnetic configuration for the CLAS12 Detector are well defined. They were developed based on: – Extensive simulation of the physics processes of the 12 GeV science program – Extensive detailed design and simulation of the CLAS12 detectors that impact the magnet design • Optics of the High Threshold Cerenkov Counter • Geometry of the Forward Silicon Detector • Geometry and design of the Polarized target – Extensive background simulations to calculate the rates and radiation doses on the central detectors (TOF and SVT) and on the forward detectors (SVT, HTCC, Drift Chambers) to make sure of the