Machine Induced Background with BCM1F 2015

The Fast Beam Condition Monitor BCM1F consists of 24 single-crystal CVD 5 mm x 5 mm diamonds positioned 1.8 m on either side of the interaction point at a radius of 6.5 cm from the beam pipe. The signal is read out, shaped by a frontend ASIC, and converted to an optical signal which is then transmitted to the backend electronics in USC55. The data travels parallel paths: a discriminator path registers the time of signal pulses and transfers this information to dedicated fast readout electronics, while an ADC system captures full orbits for monitoring studies but is prevented from acting as data readout by a high deadtime. BCM1F provides information on the condition of the beam and ensures that the inner detector occupancy is sufficiently low for data-taking. Measurements of the machine induced background for beam 1 (BKGD1) and beam 2 (BKGD2) are displayed in the CMS and LHC control room. The background data correlates the with collimator settings as well as with the vacuum pressure.