1. kinematics Opportunities and issues 1F. Fleuretfixed-target projects at CERN

2. Luminosity F. Fleuret2 Intensity: expect 5.10 8 protons.s -1 – Beam: 2808 bunches of 1.15x10 11 protons = 3.2x10 14 protons – Bunch: Each bunch passes IP: 3.10 5 km.s -1 /27 km ~ 11 kHz – Instantaneous extraction: IP sees 2808 x 11000~3.10 7 bunches passing every second  extract 5.10 8 /3.10 7 ~ extract 16 protons in each bunch at each pass – Integrated extraction: Over a 10h run: extract 5.10 8 p x 3600s.h -1 x 10h=1.810 13 p.run -1  extract 1.8 x 10 13 /(3.2 x 10 14 )~5.6% of the protons stored in the beam Instantaneous Luminosity L = N beam x N Target = N beam x (  x e x N A )/A – N beam =5 x 10 8 p + /s – e (target thickness) = 1 cm Integrated luminosity – 9 months running/year –  1year ~ 10 7 s –   year L = L inst x10 7 Intensity: expect 5.10 8 protons.s -1 – Beam: 2808 bunches of 1.15x10 11 protons = 3.2x10 14 protons – Bunch: Each bunch passes IP: 3.10 5 km.s -1 /27 km ~ 11 kHz – Instantaneous extraction: IP sees 2808 x 11000~3.10 7 bunches passing every second  extract 5.10 8 /3.10 7 ~ extract 16 protons in each bunch at each pass – Integrated extraction: Over a 10h run: extract 5.10 8 p x 3600s.h -1 x 10h=1.810 13 p.run -1  extract 1.8 x 10 13 /(3.2 x 10 14 )~5.6% of the protons stored in the beam Instantaneous Luminosity L = N beam x N Target = N beam x (  x e x N A )/A – N beam =5 x 10 8 p + /s – e (target thickness) = 1 cm Integrated luminosity – 9 months running/year –  1year ~ 10 7 s –   year L = L inst x10 7 Targ  (g.cm -3 ) A L inst (  b -1.s -1 )  year L (pb -1.y -1 ) Liq H0.068126260 Liq D0.16220200 Be1.85960600 Cu8.966440400 W19.118530300 Pb11.3520716160 Reach few fb -1 with 10cm liq H/D target fixed-target projects at CERN

3. Rapidity Energy – rapidity 3F. Fleuret p+p run : 7 TeV p  p : E CMS = 114.6 GeV Pb+Pb run : 2.75 TeV p  p : E CMS = 71.8 GeV p+p run : 7 TeV p  p : y CMS = 4.8 Energy Pb+Pb run : 2.75 TeV p  p : y CMS = 4.3 fixed-target projects at CERN

4. Pseudo-rapidity  * =  – y CMS forward region:  *>0 backward region:  *<0 Very high boost: – With 7 TeV beam :  = 61.1 – With 2.75 TeV beam:  = 38.3 Very well placed to access backward physics Forward physics difficult to access  * =  – y CMS forward region:  *>0 backward region:  *<0 Very high boost: – With 7 TeV beam :  = 61.1 – With 2.75 TeV beam:  = 38.3 Very well placed to access backward physics Forward physics difficult to access 4F. Fleuret 7 TeV 2.75 TeV  *=-4.5  *=-4  *=-3.5  *=0 y CMS = 4.8 y CMS = 4.3  *=-4.8  *=-4.3 fixed-target projects at CERN

5. Detector constraint Geometry – The geometry of the detector is related to the geometry of the magnet – The magnet geometry is constrained by the outgoing particle momentum – In principle If p T > p L use a solenoid If p L > p T use a dipole Geometry – The geometry of the detector is related to the geometry of the magnet – The magnet geometry is constrained by the outgoing particle momentum – In principle If p T > p L use a solenoid If p L > p T use a dipole F. Fleuret5 solenoid  detector parallel to the beam dipole  detector transverse to the beam large p T particles  Solenoid is better large p L particles  Dipole is better B B B pTpT pLpL B fixed-target projects at CERN

6. Detector constraint Geometry – In principle : If p T > p L use a solenoid, if p L > p T use a dipole Converting p T =p L in rapidity frame Geometry – In principle : If p T > p L use a solenoid, if p L > p T use a dipole Converting p T =p L in rapidity frame F. Fleuret6 If p T > p L,  *<-4 If p T -4 In principle: one should use a solenoid to access  *<-4 one should use a dipole to access  *>-4 In principle: one should use a solenoid to access  *<-4 one should use a dipole to access  *>-4 pTpT fixed-target projects at CERN  pLpL p T =p L   = 45°    * = 0.88 – 4.8 ~ -4 

7. Longitudinal detector Typical detector : – -4.8 < y* < -3.5 – Multipurpose detector Vertex Tracking calorimetry Compact detector – Because of the high boost, the detector must be as compact as possible – Compact calorimeters (Calice) EMCal ~ 20 cm long HCal ~ 1 m long – Vertexing + Tracking 80 cm should be enough To be checked Typical detector : – -4.8 < y* < -3.5 – Multipurpose detector Vertex Tracking calorimetry Compact detector – Because of the high boost, the detector must be as compact as possible – Compact calorimeters (Calice) EMCal ~ 20 cm long HCal ~ 1 m long – Vertexing + Tracking 80 cm should be enough To be checked F. Fleuret7  *=-4 vertex tracking EMCal HCal solenoid fixed-target projects at CERN

8. Transverse detector F. Fleuret8 EMcal Hcal MuID ~1 m ~0.1 m~0.2 m ~1 m~2 m  *=0 fixed-target projects at CERN

9. Transverse detector Go forward ? – Possibility to access y*=1 by shifting the detectors Go forward ? – Possibility to access y*=1 by shifting the detectors F. Fleuret9 Detector Z min /Z max at  *=0 Z min /Z max at  *=1 Vertex 40/50 cm100/110 cm Tracker 50/150 cm200/300 cm EMCal 150/170 cm400/420 cm Hcal 170/270 cm500/600 cm muons 270/470 cm800/1000 cm fixed-target projects at CERN

10. Longitudinal.vs. Transverse Impossible to deal with the two magnets at the same time Two options : – limit ourself to -3.5<  *<0 (1) – build two setups Impossible to deal with the two magnets at the same time Two options : – limit ourself to -3.5<  *<0 (1) – build two setups F. Fleuret10 tracking EMCal HCal solenoid fixed-target projects at CERN Note that: Don’t need longitudinal detector !

11. conclusion LHC – Very high luminosity accessible : up to fb -1.y -1 – E CMS = 114.6/71.8 GeV in p+p/Pb+Pb – y CMS =4.8/4.3 in p+p/Pb+Pb Detector : two options – Measuring -4.8 <  *<-3.5  longitudinal/solenoid – Measuring -3.5 <  * < 0 (1)  transverse/dipole – Not possible to run both detectors at the same time, but, in principle, we don’t need to reach  *<-3.5 to access x F =-1. LHC – Very high luminosity accessible : up to fb -1.y -1 – E CMS = 114.6/71.8 GeV in p+p/Pb+Pb – y CMS =4.8/4.3 in p+p/Pb+Pb Detector : two options – Measuring -4.8 <  *<-3.5  longitudinal/solenoid – Measuring -3.5 <  * < 0 (1)  transverse/dipole – Not possible to run both detectors at the same time, but, in principle, we don’t need to reach  *<-3.5 to access x F =-1. 11F. Fleuretfixed-target projects at CERN