Fermilab Accelerator Physics Center Background Simulations at Fermilab

Fermilab Accelerator Physics Center Background Simulations at Fermilab Sergei Striganov Nikolai Mokhov and Igor Tropin Fermilab MAP 2013 Collaboration Meeting Fermilab June 19 -22, 2012

Outline • Introduction • Background spectrum and fluxes at central part of detector • Basic characteristics of backgrounds coming into detector MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

MARS 15 Modeling • Detailed magnet geometry, materials, magnetic fields maps, tunnel, soil outside and a simplified experimental hall plugged with a concrete wall. • Detector model with Bz = 4 T and tungsten nozzle, starting at ± 20. 45 cm from IP with R = 2. 8 cm at this z. ROOT geometry. • 62. 5 -Ge. V bunches of 2× 1012 m- and m+ approaching IP are forced to decay at |S| < Smax, where Smax up to 23 m at 5. 13× 106 / m rate. • Cutoff energies in this study - 0. 1 Me. V (n, gamma), 1 Me. V (charged hadrons) and 0. 5 Me. V (e+-). Cutoffs could be reduced substantively in production runs. MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

HF MDI Versions ü No nozzles, no other MDI shielding ü v 0 - minimal 7. 6 deg, 5σ nozzles ü v 1 - minimal 7. 6 deg, 5σ tungsten nozzles, tungsten collimator in IR and concrete collars in IR ü v 2 - thicker 15 deg, 4σ tungsten nozzles in BCH 2 cladding, tungsten collimator in IR, concrete colars in IR, new magnets geometry, magnetic field maps MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Machine-Detector Interface - v 2 MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Gamma Flux (1/cm 2/bunch) without nozzle MAP 13, Fermilab, June 19 -22, 2013 v 2 Background Simulation at Fermilab - S. Striganov

Electron/Positron Flux (1/cm 2/bunch) without nozzle MAP 13, Fermilab, June 19 -22, 2013 v 2 Background Simulation at Fermilab - S. Striganov

Neutron Flux (1/cm 2/bunch) without nozzle MAP 13, Fermilab, June 19 -22, 2013 v 2 Background Simulation at Fermilab - S. Striganov

Gamma Flux in Plane Perpendicular to Muon Beam Direction at IP (1/cm 2/bunch) MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

e+- Flux in Plane Perpendicular to Muon Beam Direction at IP (1/cm 2/bunch) MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Neutron Flux in Plane Perpendicular to Muon Beam Direction at IP (1/cm 2/bunch) MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Energy Spectra in Plane Perpendicular to Muon Beam Direction at IP (1/cm 2/Ge. V/bunch) r<50 cm gamma MAP 13, Fermilab, June 19 -22, 2013 electron/positron Background Simulation at Fermilab - S. Striganov

Energy Spectra in Plane Perpendicular to Muon Beam Direction at IP (1/cm 2/Ge. V/bunch) r<50 cm neutron MAP 13, Fermilab, June 19 -22, 2013 charged hadron Background Simulation at Fermilab - S. Striganov

Background File Simulation of background particles coming into detector takes a lot of CPU. To look at detector background in detail file with particles on some interface surface is prepared. Different detector geometries and different codes (Geant 4, Fluka) can be used in further studies starting from this file. Muon decay points are simulated randomly from -10 to 23 m from IP using MARS code. Electron/positron shower in accelerator structure is simulated. Calculation is stopped at interface surface. Following results were obtained with cutoff energies (± 23 m from IP): gamma, neutron - 100 ke. V, charged hadron - 1 Me. V, e± - 500 ke. V, muon – 1 Me. V. MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Where is Background Produced? Number of Particles Entering Detector MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Number of particles per bunch crossing entering detector Particle 10 deg (750 Ge. V) v 0 (62. 5 Ge. V) v 2 (62. 5 Ge. V) 7. 51515 Photon 1. 8 x 108 8. 1 x 109 3. 2 x 109 Electron 1. 0 x 106 3. 0 x 108 1. 2 x 108 Neutron 4. 1 x 107 3. 2 x 108 1. 7 x 108 Charged hadron 4. 8 x 104 3. 0 x 106 1. 0 x 105 MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Where is Background Produced? Energy Flow Entering Detector MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Energy (Te. V) per bunch crossing entering detector Particle 10 deg (750 Ge. V) v 0 (62. 5 Ge. V) v 2 (62. 5 Ge. V) 7. 51515 Photon 1. 6 x 102 4. 6 x 104 1. 2 x 104 Electron 5. 8 4. 2 x 104 9. 0 x 103 Neutron 1. 7 x 102 6. 9 x 102 3. 0 x 102 Charged hadron 12 1. 2 x 102 26 MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Momentum Spectra of Particles Entering Detector MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Average momentum (Me. V/c) of particle entering detector Particle 10 deg (750 Ge. V) v 0 (62. 5 Ge. V) v 2 (62. 5 Ge. V) 7. 51515 Photon 0. 9 3. 8 2. 8 Electron 6 29 16 Neutron 45 40 38 Charged hadron 513 662 444 MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Time Distribution wrt Bunch crossing at Detector Entrance MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Where is Background Enters Detector? 70% gamma, 80% e+-, 60% of hadrons coming into detector through quad (Z>350 cm and R > 350 cm) – more than 15 ns from IP. MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Where is Energy Enters Detector? 40% gamma, 40% e+-, 60% of hadrons coming into detector through quad (Z>350 cm and R > 350 cm) – more than 15 ns from IP. MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Time distribution wrt Bunch crossing at Detector Entrance (|Z| > 350 cm) 90% gamma, e+-, charged hadrons coming into detector through quad (Z>350 cm and R > 350 cm) can be rejected by 15 ns time gate MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Summary ü Background loads in tracker and vertex detector can be substantially reduced by 15 degree & 4σ tungsten nozzle with borated poly cladding ü About 70% of background particles enter into detector at large distance from IP (> 350 cm) before shielding nozzle through first quad. Influence of this background can be reduced by timing cut depending on detector position. If this way is not effective enough additional shielding and reduction of detector sensitive volume at large angle should be considered ü Beam-line description should be improved by adding more elements to correct estimate muon background ü Simulation of hits in tracker/vertex detector are needed to understand is achieved background in acceptable level MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Backup MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov

Where is Background Produced? Number of Particles Entering Detector MAP 13, Fermilab, June 19 -22, 2013 Background Simulation at Fermilab - S. Striganov