ALICE and LHCb Crossing angle and polarity first aid

1. ALICE and LHCb Crossing angle and polarity first aid ALIC and LHCb angle and polarities - JW

2. Angles, knobs, polarities (*) full xing angle corresponds to twice those values. Nominal values. ALIC and LHCb angle and polarities - JW KNOB settings @ full field (injection, KNOB = xing angle with 2010 FIDEL calibration): ALICE: KNOB = 1049.08 mrad I = 6000 A LHCb: KNOB = 2095.83 mrad I = 5850 A

3. ALICE polarities and crossing angles Superposition of the external and internal Xing angles can be compensating (opposite signs) or additive (same signs). ALIC and LHCb angle and polarities - JW For 2011 high intensity proton running, the configurations where the internal and external angles add up must be used (magenta).

4. LHCb ALIC and LHCb angle and polarities - JW Spectrometer • Example of the LHCb spectrometer bump corresponding to: • NEGATIVE internal Xing angle (B1 moving inwards), • POSITIVE spectrometer kick (B1 kicked outwards), • POSITIVE spectrometer PC POLARITY.

5. LHCb polarities and crossings ALIC and LHCb angle and polarities - JW • For 2011 high intensity proton running, the configurations where the external angle is negative will be used (magenta). • For positive polarity the internal angle adds to the external angle – the preferred configuration (for us). • For negative polarity the internal angle partly compensates the external angle.

6. Spectrometer bump in MADX LSA K: refers to the ratio of magnet kick / crossing angle. In 2010 the magnet calibration curves were revised (FIDEL team). In RED the nominal crossing angle at 7 TeV ALIC and LHCb angle and polarities - JW

7. Contacts Exp. Magnet contacts: ALIC and LHCb angle and polarities - JW