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SPS North Area Operation Shutdown Lectures - 2006

SPS North Area Operation Shutdown Lectures - 2006. Morning session Introduction and test beams Ilias Efthymiopoulos Afternoon session M2 muon beam – COMPASS Lau Gatignon Neutrino beam – CNGS Edda Gschwendtner And… PS East Area operation M. Delrieux (17 March – PM)

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SPS North Area Operation Shutdown Lectures - 2006

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  1. SPS North Area Operation Shutdown Lectures - 2006 Morning session Introduction and test beams Ilias Efthymiopoulos Afternoon session M2 muon beam – COMPASS Lau Gatignon Neutrino beam – CNGS Edda Gschwendtner And… PS East Area operation M. Delrieux (17 March – PM) nTOF/FTN line operation not operational in 2006

  2. The SPS North Area Beams Outline Introduction (6) The EHN1 Beams (18) Design highlights (12) Operational aspects (4) Safety Issues (8) Access System Ilias Efthymiopoulos AB/ATB-EA SPS Training Lecture Program March 2006

  3. Introduction (1/6) • The proton beam (400 GeV/c) from SPS is slowly extracted to the North Area at LSS2 • The extracted beam is transported in the TT20 tunnel • 11% slope to arrive into TCC2 – then horizontal ; ~10m underground • The primary proton beam is split in three parts directed towards to the North Area primary targets: T2, T4 and T6 11% slope ie-spstraining

  4. Introduction (2/6) The splitters – how they work! • Optimized beam optics to minimize losses • Small bH (~9m) and large bv(~23Km) • The beam splitters are among the “hottest” objects in TCC2 Field-free region Horizontally deflected by the B-field Continues straight - no B-field Losses T2 T4 T6 ie-spstraining

  5. Introduction (3/6) The SPS North Area Beams • The three proton beams are directed onto the primary targets: • T2  H2 and H4 beam lines • T4  H6, H8, and P0 beam lines • T6  M2 beam line and Experimental Areas: • ECN3: underground experimental hall, can receive the primary proton beam with high intensity in ECN3 • EHN1: surface experimental hall, can receive secondary beams and/or attenuated primary proton beams • EHN2: surface experimental hall, receives the secondary beams or intense muon beam ie-spstraining

  6. Introduction (4/6) EHN2 (COMPASS) EHN1 ECN3 (NA48) BA80 (ps building) TCC2 access CRN (obsolete) TCC2 targets (underground) BA81 (ps building) CCC ie-spstraining

  7. Introduction (5/6) • 6.5 Km of beam lines • About 1000 equipment installed NA49 CALICE/ILC GLAST, DREAM, AMS,… CMS ALICE CERF/SC-RP CRYSTALS/LHC Coll. TOTEM LHCb ATLAS ie-spstraining

  8. Introduction (6/6) • 2006 will be a very interesting year for operations… ie-spstraining

  9. The EHN1 beams (1/18) • The SPS North Area was originally designed to house long-lasting experiments • demands for high quality of beams: high intensity, high energy, high resolution • In the recent years most of the users are “tests” • in particular of LHC detectors with permanent or “semi-permanent” BIG installations • several users from astroparticle experiments • The test users have very different requirements from the big experiments: • scan the full energy range ; typically [10, 300] GeV/c • with sometimes increased precision (linearity) requirements • use beams of all particle types {electrons, pions, protons, muons} • with as good as possible separation and identification • and, sometimes request high (or very high) rates and all that during the few (or even one!) week(s) of their allocated time! Rapidly changing environment, quite demanding on beam conditions and tunes ie-spstraining

  10. The EHN1 beams (2/18) ie-spstraining

  11. The EHN1 beams (3/18) Particle production downstream the primary target • Protons : remnant of the incoming primary beams • the target actually serves as attenuator • ~40% of the initial incoming intensity of the beam • Pions(hadrons): produced in hadronic interactions • Typical scale: interaction length (lint) • Electrons : produced in electromagnetic processes • Typical length scale : radiation length (X0) • Muons : produced in the decay of pions • At the target and also along the beam line Primary p beam (400 GeV/c) Secondary particles ( 400 GeV/c) Target Development of hadronic shower Attenuated proton beam ie-spstraining

  12. The EHN1 beams (4/18) Target material and length • The proton intensity on each target can go up to 1013 protons/pulse • limited by target and TAX absorber construction (i.e. cooling, etc.) • The material with largest ratio: Xo/lint is preferred  Beryllium • Increasing the target length: • more production but also more re-absorption • lower the energy of the outgoing particles Optimal choice ~ 1 interaction length ie-spstraining

  13. The target head Beam position monitors TBIU (upstream) , TBID (downstream) mounted on same girder as the target head for better alignment beam steering onto the target using BSM located ~30m upstream of the target The EHN1 beams (5/18) <x> = -0.2 mm <y> = -0.4 mm ie-spstraining

  14. The EHN1 beams (6/18) T6 target (M2, COMPASS) T4 target (H6, H8, P0) T2 target (H2, H4) Wobbling magnets ie-spstraining

  15. The EHN1 beams (7/18) Special cases – tertiary beams from neutrals • Neutral particles (g, K0, L0) are also produced at the target And … • Convert the photons using a lead sheet to produce e+, e- pairs • That way we can produce the purest electron/positronbeams !!! • Let short lived neutrals (K0, L0) to decay in air to produce p or pbeams • Using the energy and decay kinematics can enhance the p, p content of the beam • Use a strong magnet to sweep away all charged particles • Let the neutrals fly through towards the beam line direction • Use the first magnet of the beam to select the sign of particles to transport ie-spstraining

  16. Special cases – Muon beam characteristics Muon beams are formed by the decay of pions (p+, or p-) Decay kinematics: At the pion center of mass system: At the laboratory frame – boost Limiting cases: Conclusion: the muon beam energy is in the interval [0.57,1.0] of the initial pion beam energy m (p*, E*) q* n m The EHN1 beams (8/18) ie-spstraining

  17. The EHN1 beams (9/18) – Production rates Hadron beams Electron beams Particle production by 400 GeV/c protons on Be targets, H.W.Atherton et. al. ie-spstraining

  18. The EHN1 beams (10/18) – target station wobbling AIM • Additional degrees of freedom  increase the flexibility in using a target station • Produce “several” secondary beams from the same target • when the primary beam hits the target basically “all” the particles are produced in a large variety of angles and energies • the most energetic particles are in the forward direction should not forget: • The very intense primary proton beam has to be dumped in a controlled way • The secondary beams of the chosen momentum have to go into the directions foreseen by the beam geometry (i.e. inside the vacuum tube of each beam line) Solution: • “wobbling” :hit the target under variable angle ie-spstraining

  19. Target Target The EHN1 beams (11/18) – target station wobbling 0-order approximation: TAX B1 • single secondary or primary beam • fixed production angle SPS protons 1st -order approximation: TAX B1 • two secondary beams • one could be the primary beam • fixed production angles SPS protons B1 2nd -order approximation: TAX B1 • two secondary beams • one could be the primary beam • variable production angles Target SPS protons B1 ie-spstraining

  20. The EHN1 beams (12/18) – T4 target station ie-spstraining

  21. The EHN1 beams (13/18) – TAX absorber attenuator ie-spstraining

  22. The EHN1 beams (14/18) –– TAX absorber attenuator Preparation and installation of new TAX blocks for T4. ie-spstraining

  23. The EHN1 beams (15/18) – T4 Wobbling Example 1: • primary proton beam in P0 • H8, H6 secondary beams ie-spstraining

  24. The EHN1 beams (16/18) – T4 Wobbling Example 1: • primary proton beam in P0 • H8, H6 secondary beams Presently the most frequent case “standard wobbling” settings: ie-spstraining

  25. The EHN1 beams (17/18) – T4 Wobbling Example 2: • P0 beam OFF • primary protons in H8 – “micro-beam” • H6 secondary beam ie-spstraining

  26. The EHN1 beams (18/18) – T4 Wobbling Safety - Survey • survey (monitor) the current in the “wobbling” magnets and the position of the TBIU, TBID monitors should be automatically done • A program called WOBSU should be running continuously • for planned changes to the target station magnets (wobbling changes) a manual INHIBIT signal for the extraction has to be set at the CCC Wobbling changes: • initiated by the EA physicist upon the user requests • presented and discussed in the EATC meeting, documented in the minutes • settings file prepared and communicated by the EA physicist • performed by the operators on the agreed time • re-tuning of the the beam lines after the wobbling changes is often required ie-spstraining

  27. The momentum selection is done in the vertical plane Design highlights (1/12) “downstream” V-BENDs (B3, B4) the main spectrometer of the beam momentum definition “upstream” V-BENDs (B1, B2) between the primary target and the momentum acceptance collimator ie-spstraining

  28. Design highlights (2/12) View of the H8 and H6 beam lines in TT81 tunnel. ie-spstraining

  29. Design highlights (3/12) Beam optics modes: • High Resolution: used in the past to increase the momentum resolution of the beam line • Required additional hardware (spectrometer chambers), not available anymore. • High Transmission: allows having the maximum particle flux at a given momentum • Filter Mode : has a focus on both planes at ~130m of the beam line, which allows using an intermediate (tertiary) target • Heavily used now days to produce tertiary beams ! • Tertiary beams provide more flexibility to the users and relaxes the coupling between the beam lines due to wobble choice. • keep longer periods with the same wobble setting ie-spstraining

  30. Design highlights (4/12) Tertiary beams • Produced in two distinct ways: • H6, H8: use a second target (filter) • beam line tuned for two energies: • E1 (high energy) : from the primary target until the filter • momentum selection by the “down” vertical BENDs • E2 (< E1) : from the filter until the experiment • momentum selection by BEND-3 and BEND-4 (up vertical bends) • H2, H4: from the conversion or decay of secondary neutral particles • tertiary muon beams of well defined momenta are produced by stopping pions in a closed collimator before the last bending magnets of the beam line ie-spstraining

  31. Design highlights (5/12) Operational aspects ie-spstraining

  32. Design highlights (6/12) Operational aspects ie-spstraining

  33. Design highlights (7/12) • introduce a target (filter) after the “upstream” bends • tertiary beams have typically lower rates • choice of target material can enhance/select different particles • Cu, Poly, Pb XCONfine positioning filter/converter ie-spstraining

  34. Tertiary beams H2 , H4 use the B3 magnet of the wobbling as sweeping magnet charged particles are absorbed in the TAX neutral particles go through and hit the converter note: neutral particles can have zero or non zero production angle use the converter g on Pb (CONVERTER=LEAD): to produce electrons (e+, e-) COPNVERTER=AIR (no converter) to let K0, L0 , to decay K0 p+ + p- L0  p + p- use B1 of the beam line to select the charge and particle for the tertiary beam to the experiment Design highlights (8/12) ie-spstraining

  35. Electron beams Secondary beams electrons produced at the primary target rate goes down with energy increase longer targets help electron production rate ~proportional to target length at high energies (120 GeV/c) can be separated from hadrons by synchrotron radiation mixed beams pion (hadron) contamination for lower energies user CEDAR or treshold Cherenkov counters for tagging Tertiary beams H6, H8: use Pb as secondary target few mm, or ~1-2 radiation lengths (X0) radiation length: distance in matter where electrons loose ~1/e of their energy hadrons loose ~nothing H2, H4: electrons from photon conversion high purity beams! Design highlights (9/12) ie-spstraining

  36. Design highlights (10/12) • Electron beam separation by synchrotron radiation at high energies 41mrad angle – DE@180 GeV/c = 200 MeV Hadron beam – no energy loss Electron beam – E0-DE @150 GeV/c  149.197 GeV/c Electron beam- E0 Electron beam- E0 41mrad angle – DE@180 GeV/c = 200 MeV ie-spstraining

  37. Hadron beams Secondary beams hadrons are produced at the primary target for positive sign beam a good fraction of the total hadron rate is protons using an absorber (~1-2 X0 of Pb) in the beam we can eliminate any electron contamination Tertiary beams H6, H8: use secondary target of Cu, (CH)n ~1 interaction length lI interaction length: characterizes the average longitudinal distribution of hadronic showers a high energy hadron has 1-1/e probability to interact within one lI lI >> X0 for most of materials H2, H4: hadrons produced in the decay of neutral mesons L0 p + p-, K0p++ p- Design highlights (11/12) ie-spstraining

  38. Muon beams Secondary beams muons produced directly at the target area or by the decay of pions muon momentum: 57-100% of the parent pion momentum to produce a pure muon beam for the experiment, is enough to close out of beam axis the last collimators of the beam line closing the collimator upstream of the last bend of the line we can obtain momentum selected muons rule of thump: muons in a 1010cm2 trigger represent ~1% of the hadron/pion flux there is another ~1% in a cone about 1  1m2 around the beam axis 106 muons / 10  10 cm2 trigger  1.3 uSv/h Tertiary beams muons present only for tertiary beams in the energy range 57-100% of the secondary beam momentum Design highlights (12/12) ie-spstraining

  39. Operational aspects (1/4) Beam tuning • Goal: deliver good quality of beam to the experiment! • sufficient rate, spot size, particle purity,… • Tuning the beam is required each time we change something: • energy, wobbling, user Very important: • start from an already prepared beam file by the EA physicists • be sure it corresponds to the present wobbling settings • be sure it can fulfil the user requirements • typically the users know “their” files, but good to check it yourself as well!!! ie-spstraining

  40. Operational aspects (2/4) The first steps • consult the logbook of the beam line • most of the files have been used already in the past • new files represent minor variations of existing files • treat each plane independently • start with the vertical plane which is the most important to get the beam to the experimental hall • select your observation point • a scintillator counter close to the end of the beam line • provided the beam can reache it!! ie-spstraining

  41. Watch out !! electrons do not like material! remove triggers or other detectors from the beam line, otherwise you may simply kill the whole beam be careful when you try to measure/monitor things, since you may disturb the users referring to logbook is fine but be sure you are comparing apples with apples follow the particles, consistent particle rates use as much as possible normalized rates: rate/pot monitor beam losses, be sure you are looking at the beam not at its halo similar rates at different places along the beam line scintillator counters are typically  = 100mm but NOT ALL; Exp. Scalers can vary a lot! switching beam files: secondary beams have high rates  acceptance collimators close tertiary beams have low rates  acceptance collimators wide open therefore: switching from tertiary to secondary beam, load FIRST the collimators and then the magnets Operational aspects (3/4) Operational aspects ie-spstraining

  42. Important Think before acting To first order, all beam lines are quite similar however there are some differences which need time to become familiar with Time is important for you and the users there is always a limit to how good a beam can be; let the users decide Some users are quite experienced with their beam, and can do many things alone Good documentation is vital beam line snapshot: status of magnets/files/wobbling settings status of collimators, target, absorber rates in few counters (start, middle, end of beam line) Don’t be afraid to ask for help Operational aspects (4/4) Operational aspects ie-spstraining

  43. Safety Issues (1/8) Radiation Safety Issues Direct in-beam exposure should be avoided at all cases! • Hadron or electron beams containing >108 particles/burst are dangerous • should be always dumped in special (thick) dumps (controlled losses) • serious irradiation to persons standing close to unshielded loss points • unshielded loss points will cause excessively high radiation levels in the experimental hall and cause dose rate limits at the CERN boundaries • any in-beam exposure for even one pulse will cause observable biological damage • beam line & areas should be completely shielded • Hadron or electron beams containing >106 particles/burst should be treated with respect • unshielded loss points will cause limiting radiation levels in the experimental halls and at the CERN boundaries • all loss points must be completely shielded (dumps) • any in-beam exposure is still serious and will cause significant administrative actions ie-spstraining

  44. Safety Issues (2/8) Radiation Safety Issues • Hadron or electron beams containing <104 particles/burst • could be allowed to travel in open areas • still in-beam exposure should be avoided • Heavy ion beams of any intensity • cannot be allowed to travel through open areas • accidental in-beam exposure is dangerous and must be completely avoided ie-spstraining

  45. Safety Issues (3/8) SC/RP Central DAQ • All installed radiation alarm monitors can be read remotely • Data are stored in a database for further retreival • The parameters for each monitor are accessible • can only be set/modified by authorized persons (TIS/RP) ie-spstraining

  46. Safety Issues (4/8) ie-spstraining

  47. Safety Issues (5/8) Additional radiation sources in the areas Radioactive sources • Used by the experiments for their detector calibration • Transport/installation under the TIS/RP responsibility • Normally a garage position should be available • sometimes the source is in interlock with the area access system • Warning panels at the door of the experimental area Lasers • Used by the experiments for their detector calibration • Normally setup certified by TIS/RP Radioactive detectors • Uranium calorimeters (not anymore “a la mode”!) • “hot” detectors after irradiation tests • transport/installation under TIS/RP supervision Note • Setups are modified quite often by the users • it can happen that information on the changes arrives very late ie-spstraining

  48. Dumps Used to orderly stop the hadron/electron beams muons go through but undergo multiple scattering ==> larger cone Typically formed by 2-3 m of iron with at least 80cm in each direction from the beam impact point one or two concrete blocks (80cm each) in each direction Several dumps can exist in a beam line provide separation between different experimental areas motorized or build in fixed dump at the end of each line For high intensity beams the dump is made re-entrant, the particles are dumped into a hole, in order to reduce the particle backsplash For very high intensities or for special beams (neutrino or muon beams) the dumps consist of many meters of iron, concrete and/or earth shielding examples: M2, P0/NA48, WANF, CNGS Safety Issues (6/8) ie-spstraining

  49. Motorized dumps XTDX – horizontal 2-3m of cast iron several blocks one next to the other variable configuration replace by concrete the last block for better neutron absorbtion No concrete shielding around it reinforced shielding in the area XTDV – vertical 3.2m of cast iron Is embedded in concrete shielding > 80cm in each direction Safety Issues (7/8) ie-spstraining

  50. Safety Issues (8/8) Fences • Used to mark the limits of the controlled areas • at least 2m height • should not be possible to climb over • no ladders allowed at any point against the fences • At least 1-2 m away from the nominal beam axis • exact size/shape depends on the size of the experiment Modification to dumps or fences • Can ONLY be initiated by the responsible physicist • Have to be approved by TIS/RP and RSO • presented in AB Safety Committee for approval • During SPS operation if for whatever reason the dumps or fences of the areas have to be modified, the MANUAL VETO of the beam line should be set ie-spstraining

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