Design, Performance and Calibration of the CMS Forward Calorimeter Wedges

We report on the test beam results and calibration methods using charged particles of the CMS Forward Calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (3\l |\eta| \le 5), and is essential for large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h \approx 5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as a/\sqrt{E} + b. The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%

Determination of the branching ratio of\u3c1 0\u2192+\u3bc 12 in the coherent dissociation \u3c0 12\u2192\u3bc+\u3bc 12\u3c0 12 and \u3c0 12\u2192\u3c0+\u3c0 12\u3c0 12

In the diffraction dissociation of \u3c0- into \u3bc+\u3bc-\u3c0- on a Cu nucleus at 50 GeV/c, the cross section {Mathematical expression} for the 1+S(\u3c10\u3c0) wave was measured. The branching ratio of \u3c10\u2192\u3bc+\u3bc- could be calculated from the ratio of this and the corresponding cross sections in the diffraction dissociation of \u3c0- into \u3c0+\u3c0-\u3c0-. The obtained value {Mathematical expression} is in good agreement with the branching ratio {Mathematical expression}, as expected if e\u3bc universality holds