Crossing angle and polarity first aid ALICE and LHCb Crossing angle and polarity first aid ALIC and LHCb angle and polarities - JW 21/2/2011

Angles, knobs, polarities Experiment Xing angle* (mrad) Energy (GeV) ALICE 1077 450 138 3500 LHCb 2106 270 (*) 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 Experiment Polarity Sign of internal Xing angle ALICE Positive Negative LHCb 21/2/2011

ALICE polarities and crossing angles Superposition of the external and internal Xing angles can be compensating (opposite signs) or additive (same signs). External Xing Polarity Internal Xing Net effect Positive Negative Compensation Addition 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). 21/2/2011

LHCb Example of the LHCb spectrometer bump corresponding to: 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. 21/2/2011

LHCb polarities and crossings External Xing Polarity Internal Xing Net effect Positive Negative Compensation Addition 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. 21/2/2011

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 Exp Magnet MADX Kick (murad) LSA K 2009 (murad/murad) LSA K 2010 (murad/murad) ALICE (V) abxwt.l2 -77.259 -1.104 -1.1044 70 murad abwmd.l2 +147.259 +2.104 +2.1055 abaw.r2 -133.547 -1.908 -1.9595 abxwt.r2 +63.547 +0.908 +0.9313 Sum kick -0.027 LHCb (H) abxws.l8 -45.682 -0.3384 -0.3386 -135 murad abxwh.l8 +180.682 +1.3384 +1.3394 ablw.r8 -180.682 -1.3384 -1.3452 abxws.r8 +45.682 +0.3384 +0.3543 0.0099 ALIC and LHCb angle and polarities - JW 21/2/2011

Contacts Magnet Person Group ALICE spectrometer Xavier Pons PH/DT Exp. Magnet contacts: Magnet Person Group ALICE spectrometer Xavier Pons PH/DT LHCb spectrometer Nicolas Bourgeois ALIC and LHCb angle and polarities - JW 21/2/2011