Detector Design

From Electron Ion Collider

This page gives a summary of what thoughts have gone into the detector design for the specialized eRHIC detector.

Contents 1 Central Detector 2 Forward Spectrometers 2.1 Forward Electron Spectrometer 2.2 Forward Hadron Spectrometer 3 Interaction Region Design

Central Detector

The central detector is designed following other collider detectors, with the difference that more emphasis is given to particle identification and to have similar angular coverage for tracking and calorimetry.

This design has been implemented in Geant3.
A detailed listing of the various subsystems as currently implemented are given in this table.
Images of the subsystems from Geant and their dimensions are given here.

The basis of the detector design and questions still under study are:

• Tracking:
  • Vertex detector: modeled following the [ZEUS micro-vertex detector].
    • As we are planning to have pixel detectors like the ones proposed for [STAR and ILC] the material can be reduced at a certain moment.
  • Barrel tracking: modeled according to the [BaBar barrel drift chamber].
  • Forward tracking: modeled according to the [HERMES forward drift chambers].
    • For both tracking detectors there are a lot of different ideas like GEM trackers or .....

• PID:
  • DIRC: modeled according to [BaBar DIRC].
    • It still needs to be studied, if modern high resolution ToF systems would not also good enough.
  • RICH: modeled according to the [HERMES dual radiator RICH] ([Aeroge]).
    • A RICH is needed in both directions because at high Q2 for very symmetric beam energies the Hadrons go backwards especially the ones with high z
    • It needs to be investigated more PID is needed for lepton hadron separation than a RICH and EMCal can provide.

• Calorimetry:
  • ECAL: lead glass blocks (10x10x50 cm³) (F101).
    • Also here quite some different technologies could be used, like spacal type ones for the barrel and lead-tungsten crystals in the forward direction.
    • The question to answer is whether we need a high resolution preshower to separate high energy π⁰s from single gammas.
  • Hadronic calorimeter: not yet modeled, but the idea is to have an ILC-like hadronic calorimeter, which combines hadronic calorimetry with muon identification.

• Magnetic Field:
  • Solenoid with 4 T.
    • Do we really need 4 T or is 2-2.5 T enough?

• Beam-Pipe:
  • Need to add what we model .

Forward Spectrometers

In the hadron and lepton beam directions we will have forward spectrometers to allow detection of particles from nuclear breakup of the proton/neutron from exclusive reactions in ep and the detection of the scattered lepton for quasi-real photoproduction physics.

Forward Electron Spectrometer

The forward electron spectrometer consists of a dipole, with YY Tesla, with tracking chambers modeled the same way as the forward tracking chambers in the central detector. In addition we have an ECal, which currently is modeled as the ECal in the central detector.

Forward Hadron Spectrometer

In the hadron direction the beam is going through 3 quadrupoles and one dipole with ±5 mrad acceptance. The dipole is followed by a zero degree calorimeter to detect neutrons and by Roman pots to detect the proton from nuclear breakup or from elastic-diffractive physics in ep.

Interaction Region Design

To get and idea about the interaction region design please have a look to the the following to presentations: [1] and [2]. The L* for the detector is ±4.5 m with a luminosity of 1.5 x 10³⁴ cm^-2s^-1.