Luminosity measurement at Adone by single and double bremsstrahlung

Single Bremsstrahlung luminosity measurements at DAΦNE

“…Thus, by comparing the theoretical and experimental spectra the measurement calibration can be achieved. A complete description of the calibration process is reported in [8]; hereafter only the essential issues are described. In the process it is used the so-called modified spectrum that is obtained by multiplying the energy differential GB cross-section by the photon energy.…”

“…The final aim of the procedure is to calibrate the abscissa variable x. It has been demonstrated [8] that, in the case of a gaussian DRF with arbitrary standard deviation, the ordinate y max of the modified spectrum corresponding to k max , see Figure 1, is always given by:…”

“…Good candidates are small angle bhabha scattering (BB), single bremsstrahlung (SB) and double bremsstrahlung (DB). Differential and integrated cross-sections for BB, DB and SB are reported in references [5,6,7]; an interesting comparison among measurements with the three different processes can be found in reference [8]. At DAΦNE SB was chosen because it better fulfills requirements i) and ii) [4] and ensures measurements at a few percent level when an efficient background subtraction method is used.…”

“…The current ratio can be obtained in two different ways: by a bunch by bunch current monitor that continuously measures and updates the ratio value or by sampling the GB produced by the two bunches in a point where the beams are not in collision. In fact, according to (8), the ratio of the GB counting rates is equal, in this situation, to the ratio of the currents. The MBBS method as described allows luminosity measurements in the case where only one bunch per beam is in collision.…”

“…This is not necessary when the second method of background subtraction is used. The Missing Bunch Background Subtraction (MBBS) is a variation of the method described in reference [8]. In DAΦNE the following configuration has been adopted.…”