The techniques for the optical calibration of Jefferson Labs large-acceptance magnetic hadron spectrometer, BigBite, have been examined. The most consistent and stable results were obtained using a method based on singular value decomposition. In spite of the complexity of the optics, the particles positions and momenta at the target have been precisely reconstructed from the coordinates measured in the detectors by means of a single back-tracing matrix. The technique is applicable to any similar magnetic spectrometer and any particle type. For 0.55 GeV/c protons, we have established a vertex resolution of 1.2 cm, angular resolutions of 7 mrad and 13 mrad (in-plane and out-of-plane, respectively), and a relative momentum resolution of 1.6%.
|Number of pages
|Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
|Published - 11 Sep 2012
Bibliographical noteFunding Information:
This work was supported in part by the U.S. Department of Energy and the U.S. National Science Foundation . It is supported by DOE contract DE-AC05-06OR23177 , under which Jefferson Science Associates, LLC, operates the Thomas Jefferson National Accelerator Facility. The UK collaborators acknowledge the funding by the UK Engineering and Physical Sciences Council and the UK Science and Technology Facilities Council .
- Magnetic spectrometers
- Optical calibration
- Track reconstruction