Hi Ed,
Below follows a short description of what I would like to see investigated in the context of the HATA-project.
The luminosity should not matter too much because it is never too low and hopefully not too high in view of the solid angle covered by the scintillators. Of course a 3He target would be perfect. Hydrogen is the worst because there are no direct protons coming out at backward angles. For the rest the Z-dependence is hard to guess.
Proposed Detector:
- HADRON2 detector (or something similar in dimensions) as close as possible to the target at an angle of about 130 degree with respect to the downstream beam.
- Assuming the use of HADRON2:
equip with PM's only the following number of channels:
| Minimum | Optimal | |
|---|---|---|
| Hod1 | 2 | 4 |
| Hod2 | 2 | 3 |
| L1 | 1 | 2 |
| L2 | 1 | 2 |
| L3 | 1 | 2 |
| L4 | 1 | 2 |
| L5 | 1 | 2 |
| Total | 9 | 17 |
- Assuming the use of HADRON2:
Choose the following thresholds:
* Hod1 (0.5 cm thick) such that protons of 200 MeV, that make it to the back of L5 are still triggering. Such protons deposit 2.3 MeV. Take a factor of 2 for attenuation in the scintillator, so set threshold at about 1 MeV. Minimum ionizing particles deposit about 1 MeV also.
* L1 (1 cm thick) set threshold according to the same reasoning as given above for Hod1. Here the attenuation is less, so the contamination of m.i.p.'s should be in principle less.
* L2, L3, L4 and L5 (3, 5, 7 and 7 cm thick) set thresholds as low as possible.
Proposed experimental conditions:
- Vary absorber thickness in front of Hod1: 1 mm Pb, 2 mm Fe, 1 mm Fe, 1 mm Al (Who can invent (and construct !) a remote-controllable absorber changing system ?? Readout of which one is in place can be done with a camera.)
- Measure at 2 beam currents, to check scaling with I.
- Measure at 2 distances, to investigate 1 over r^2 behviour.
- If possible measure at 2 target thicknesses, to vary multiple scattering in the target.
- Measure also with no-target.
Data to be collected:
- Measure singles rates of all counters.
- measure ADC and TDC info of all channels while triggering on:
* L1 only
* H1xL1 coincidence
eddy jans
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