NLD Simulations

Introduction Detector simulation work following on to the NLD spec that came out of Snowmass '96 is targetted, at least initially, towards a compact detector emphasizing precision tracking with a Si pixel vertex detector plus Si strip central tracker and calorimetry built around a Si-W EM calorimeter all bathed in a 4T field. The design spec has been extracted to give easy access to the components. The current issues center around the feasability of the compact calorimeter. It is assumed that the tracking performance can be understood easily enough through simple parametrizations; full simulations are needed for the calorimetry.

Sample multiparticle event.

Some thought has been put into a strategy for starting these studies. The operating decision was made to avoid existing detector infrastructures and invest in modern tools to avoid alienating collaborators and prepare for new technologies. The work has begun using C++ and GISMO to provide the full simulation of the calorimetry.

Reference Links:

• NLC
• Gismo
• Procedures

Initial Simulation Details

The initial geometry involves only the calorimetry in approximate form: layers are cylinders and there are no cracks in the barrel or endcap devices.  Material data was generated using the PEGS preprocessor for EGS.

Below are the assumptions made about dimensions in the EM and HAD calorimeters.

Geometry summary

• Radiator definitions:
  • EM
    • 0.3 cm W (0.85 X₀)
    • 0.03 cm Si
    • 0.1 cm G10
    • 0.05 cm air gap
  • HAD
    • 1 cm Fe
    • 0.4 cm scintillator
    • the 100 samples are to be ganged into 3 readout layers. So far, this has not been done.

  	rin(cm)	rout(cm)	Layers	length(cm)	j seg	Dj	Wj(rin) (cm)	tanl seg	Dtanl	Wtanl(rin)
  EM barrel	49	66.9	37	125	300	0.021	0.8	300	0.024	1.0
  EM endcap	15	48	31	15 (inner z = 110)	300	0.021	0.8	300	0.024	1.0
  HAD barrel	80	225	100	125	60	0.1	4.	60	0.122	5.
  HAD endcap	17	225	100	150 (inner z = 125)	60	0.1	4.	60	0.122	5.

• Coil
  • r_in = 70 cm, r_out = 80 cm
  • B= 4 T inside r_in, 0 in the solenoid itself and -0.4 T outside r_out
• Tracking
  • tracks are just smeared McParticle parameters who pass within the acceptance of | cosq | < 0.99.
  • Momentum smearing is p_i = p_i (1 + G*0.0015), where G is a Gaussian random number of unit width and the p_i are the components of the momentum vector.

Readout Issues:

• I/O currently happens at the digization phase of simulation and merely lists the tower identifiers and deposited energies. The ASCII format is:
  • event marker
    event number string
    device name
    number of channels
    list of ID, energy - one pair per line
    <next device>
  • ID's are defined as:
    • ID = layerx10⁵*L + I_j + Seg_j tanl
      • where I_tanl = Int(tanl+tanl_max)/Dtanl) and
      • I_j = j/Dj
      • L = l + l_offset
        • l_offset ={0,100,200) for {barrel, SEC, NEC}
        • l is the layer number.
• These ASCII files are then translated to PAW CWNtuples for analysis.

Status & Updates

Richard Dubois Last Modified: 01/13/04 12:54