BeAST Detector (Brookhaven eA Solenoidal Tracker) Alexander Kiselev for the BNL EIC taskforce Berkeley EIC User Group Meeting Jan’2016

Jan,7 2016A.Kiselev RHIC -> eRHIC upgrade proposal 2/18 by 2025 convert RHIC to an electron-ion collider by replacing one of the proton rings by up to ~21 GeV electrons (arXiv ) Yesterday talk by Thomas Roser

Jan,7 2016A.Kiselev Two viable eRHIC detector options 3/18  Upgrade PHENIX to ePHENIX  Build a new detector

Jan,7 2016A.Kiselev A “perfect” DIS detector requirements 4/18  The more close to 4  acceptance the better  Reach in kinematic variables  Reliable electron identification  Good hadron PID  High spatial resolution of primary vertex  Low material budget  Luminosity and polarization measurement  Close-to-beam-line acceptance add-on detectors in order to register:  recoil protons  low Q 2 electrons  neutrons in hadron going direction See yesterday talk by Elke Aschenauer for a complete list of requirements

Jan,7 2016A.Kiselev5/18 hadronic calorimeters electrons 9.0m TPC e/m calorimetersRICH detectors silicon trackersGEM trackers3T solenoid coils BeAST detector layout ALICE EIC R&D (UCLA, BNL) CBM SBS EIC R&D (UCLA, BNL) hadrons -4<  <4: Tracking & e/m Calorimetry (hermetic coverage)

Jan,7 2016A.Kiselev Tracker elements 2x7 disks with mm radius; same building blocks as in vertex forward/backward silicon trackers: TPC: GEMs: ~2m long; gas volume radius [ ] mm 1.2% X 0 IFC, 4.0% X 0 OFC; 15.0% X 0 end-caps assume 5 mm long GEM pads and  m s.p. {r  } resolution 3 disks behind the TPC end-caps; SBS design assume 50  m resolution 6/18 silicon vertex tracker: 2x2 barrel layers; ALICE ITS design (MAPS-based) assume discrete 20x20  m 2 pixels and ~0.3% X 0 per layer

A.Kiselev7/18  High resolution up to (at least) |  |~3  High redundancy  Low material budget Variations: MuMegas barrels, smaller TPC radius, … Jan, Tracker performance & properties  EIC R&D (Saclay) Momentum resolutionRadiation length scan 2.0m

Jan,7 2016A.Kiselev Smearing in DIS kinematic variables 8/18  {PYTHIA 20x250 GeV, NO bremsstrahlung} -> {GEANT} -> {Kalman filter track fit}  same procedure; simulation WITH bremsstrahlung -> looks good despite poor resolution at low Y and long bremsstrahlung tails

Jan,7 2016A.Kiselev “Purity” in (x,Q 2 ) kinematic bins 9/18  Describes migration between kinematic bins  Important to keep it close to 1.0 for successful unfolding bremsstrahlung OFFbremsstrahlung ON  Bremsstrahlung matters even for detector with ~5% X/X 0  “Straightforward” lepton tracking can hardly help at Y<0.1  Use scattered lepton tracking information only

Jan,7 2016A.Kiselev “Purity” in (x,Q 2 ) kinematic bins, cont’d 10/18  Assume e/m calorimeter with energy resolution ~5%/ √ E is used in addition to tracking  Consider “bremstrahlung off ” case for simplicity tracking onlytracking + EmCal -> a good EmCal clearly helps to extend useful Y-range

Jan,7 2016A.Kiselev “Purity” in (x,Q 2 ) kinematic bins, cont’d 11/18 Electron-only methodDouble-angle method  Make use of hadronic final state information  Consider “bremstrahlung on” case here -> hadronic final state accounting also helps to extend useful Y-range (and also other methods were employed at HERA)

Jan,7 2016A.Kiselev e/m calorimeter modeling -> good agreement with original MC studies and measured data Tungsten powder scintillating fiber technology; straight (endcap) and tapered (barrel) geometry 12/18

-energy resolution comparable to ZEUS 1987 paper HCal EmCal 12 GeV pions: Hcal vs EmCal Slope ~1.20 perfectly matches measured data - GEANT4, FTFP_BERT physics list - Birk’s correction accounted Hadronic calorimeter modeling Jan, /18 A.Kiselev Lead absorber scintillating plate sandwich technology

Jan,7 2016A.Kiselev14/18 -> field maps, magnet aperture locations and sizes available -> Roman Pots, Low Q 2 tagger & Lumi Monitor implemented FFAG bypass Roman Pots location Low Q 2 tagger location Main detector Electron beam line Hadron beam line Interaction Region implementation See talk by Richard Petti tomorrow

Jan,7 2016A.Kiselev Solenoid field modeling OPERA 2D/3D software used Multi-Ring Solenoid configuration(s) Presently used design: MRS-B1 15/18

Neutron flux estimation  Import STAR experiment geometry (including experimental hall)  Run ep- and pp-PYTHIA simulations for STAR and BeAST setups  Use direct STAR neutron flux measurements from 2013 as a reference STAR geometry imported in EicRoot BeAST detector placed in STAR hall Strategy: At most ~10 10 n/cm 2 per year of running at L=10 33 cm -2 s -1 n/cm 2 / 1MHz PYTHIA 20x250 GeV ep-events Jan,7 2016A.Kiselev 16/18

Jan,7 2016A.Kiselev Track finder/fitter for forward angles 17/18  Recently written in EicRoot for STAR forward upgrade project (6 silicon strip disks)  Successfully handles few hundred tracks per event in pseudo-rapidity range [ ] -> no doubts should work fine on a handful of tracks per DIS event in a more favorable BeAST pixelated MAPS- based forward/backward silicon tracker geometry

Jan,7 2016A.Kiselev Summary slide 18/18  A flexible eRHIC detector simulation framework developed  Ongoing work:  Physics process simulations  Realistic RICH detector implementation(s)  PID algorithm development  Track finder implementation for central rapidities  Further optimization of various detector technologies to meet the detector requirements imposed by physics

Backup Jan,7 2016A.Kiselev 19/16

Lepton PID requirements E.C. Aschenauer EIC User Meeting, Berkley, Lepton-PID:  suppression: the same  coverage for tracking & Ecal h - suppression through E/p  <-4: 1:1 -4<  <-1: 10:1 to 10 3 :1  <1: 10 4 :1

SIDIS: Pion Kinematics Jan, Cuts: Q 2 >1 GeV 2, Increasing hadron beam energy influences max. hadron energy at fixed  (and  , K ±, p ± look the same) A.Kiselev Increasing lepton beam energy boosts hadrons more to negative rapidity -3<  <3 covers entire p t & z region important for physics

Lepton Kinematics and (x,Q 2 ) coverage Jan,  Q 2 > 1.0 GeV 2 : rapidity coverage -4 <  < 1 is sufficient  Q 2 < 0.1 GeV 2 : a dedicated low-Q 2 tagger is required A.Kiselev Increasing lepton beam energy: scattered lepton is boosted to negative  high y-coverage limited by radiative corrections -> can be suppressed by requiring hadronic activity low y-coverage limited by E’ e resolution -> use hadron or double angle method to reconstruct event kinematics

Kinematic Coverage of Pions E.C. Aschenauer EIC User Meeting, Berkley, Cuts: Q 2 >1 GeV 2, GeV -3<  <3 covers entire kinematic region in p t & z important for physics no difference between  , K ±, p ±

Exclusive Reactions 24 proton/neutron tag method o Measurement of t o Free of p-dissociation background o High acceptance for Roman Pots / ZDC challenging  IR design Diffractive peak Large Rapidity Gap method o X system and e’ measured o Proton dissociation background o High acceptance in  for detector MYMY Q2Q2 How can we select events: two methods Need Roman Pot spectrometer and ZDC Need HCal in the forward region Jan,7 2016A.Kiselev Cuts: Q 2 >1 GeV, 0.01<y<0.85 DVCS – photon kinematics increasing Hadron Beam Energy: influences max. photon energy at fixed  – photons are boosted to negative rapidities (lepton direction)

Requirements from Physics Jan, Hadron-going direction: 1.detection of neutrons from nuclear break up  location/acceptance of ZDC (<4 mrad) 2. detection of scattered protons from exclusive and diffractive reactions;  location/acceptance of RP (<5 mrad); A.Kiselev 3.beam element free region around the IR 4.minimize impact of detector magnetic field on lepton beam  synchrotron radiation Lepton-going direction: 1.space for low Q 2 scattered lepton detection 2.space for the luminosity monitor in the outgoing lepton beam direction 3. space for lepton polarimeter detector acceptance:  >4.5 DVCS protons

Low Q 2 -tagger – Task: detect low Q 2 scattered electrons  quasi-real photoproduction physics Jan, e’-detector A.Kiselev  need a separate device designed similar to the JLab Hall D tagger (finely spaced scintillator array):  scattered lepton energy  -> at nominal energy can not register scattered electrons with Q 2 <0.1 in main spectrometer! DIS electron kinematics