Status of the target and beam line optimization for LAGUNA/LBNO Oxford meeting 2 nd -4 th July 2012 P. Velten, M. Calviani on behalf of the CERN-LAGUNA WG(*) M. Calviani, I. Efthymiopoulos, A. Ferrari, C. Lazaridis, P. Velten

Outlook 2 1. Objectives of the on-going studies 2. Target optimization work  Optimal configuration == physics and initial technical constraints 3. Focusing system (horn & reflector relative configuration)  Understanding the main interdependencies 4. Decay pipe  Effect of its geometry in the FD/ND spectra 5. ND and FD  and  ± background  Constraints on the hadron absorber/ND relative position 6. Summary and perspectives for future activities July 2012P. Velten, M. Calviani (CERN)

Objectives 3  Understand the sensitivity of the neutrino fluence on the different degree of freedom (meson production target and focusing system)  Setup a strategy to reiterate efficiently the optimization steps  Confine the degrees of freedom with realistic technical considerations (longer term)  Aim at converging in a feasible design (longer term) July 2012P. Velten, M. Calviani (CERN)

Target optimization: methodology 4  Primary beam interaction simulated with FLUKA  400 GeV/c proton beam impinging on a target  Scoring secondary  + yield as a function of emission angle  Yield maximization as a function of target configuration  Target radius and primary beam sigma  Material & density effect  Effect of target segmentation (à-la-CNGS) July 2012P. Velten, M. Calviani (CERN)  Solid material needed:  Low-Z material for energy deposition  High melting and sublimation points Graphite/beryllium candidate materials

Target optimization: angular selection 5  CNGS case:  E  = [20÷50] GeV   < 20 mrad  LAGUNA/LBNO:  E  = [2÷10] GeV   < 70 mrad (1 st iteration)  Next iteration will consider a larger  + acceptance (  < 100 mrad) July 2012P. Velten, M. Calviani (CERN)   + energy distribution with different angular selections  Larger population at low energy for larger angles

Target optimization: material 6July 2012P. Velten, M. Calviani (CERN)  LAGUNA/LBNO current settings does not benefit from segmentation  Might be needed from a mechanical point of view  Be slightly better performing  Higher density better for yield  higher energy deposition

Target optimization: target/beam radius 7  Maximal yield obtained for r=4-8 mm  No clear benefits for larger radiuses  Gain in lower energy  +  Reduction of thermal stresses on target  SPS optics to be matched July 2012P. Velten, M. Calviani (CERN) Configuration: 130 cm C +  =2 g/cm 3 + no segmentation Studies validated with the CNGS case

Energy deposition and peak temperatures 8  Preliminary evaluation based on a single pulse (adiabatic) approach (7*10 13 p/pulse)  Peak  T/pulse similar or less than in the CNGS case  Detailed FEM analysis (transient + steady state) to be conducted July 2012P. Velten, M. Calviani (CERN) 4 mm radius 2.5 mm FWHM Max  T~650 K 8 mm radius 5 mm FWHM Max  T~450 K

Some preliminary ideas on cooling 9  Target cooling for the 750 kW phase: 1. Radiation cooling (à-la-CNGS)  Cooling of the external body needed 2. Forced He cooling (+radiation cooling)  More efficient but technically more complex  Target should be ˚C July 2012P. Velten, M. Calviani (CERN)  Target outside horn is a major advantage  Degree of freedom in target/horn design  No problem of target/horn heat & electrical insulation  Should be set as a design constraint  50 GeV (2 MW) phase will (probably) need a new optimization

Some preliminary ideas on cooling 10  Radiation damage of graphite  Expected ~0.25 kW  At °C: dimension change and thermal conductivity are minimized  Also reduce H embrittlement July 2012P. Velten, M. Calviani (CERN)  He gas cooling:  High target temperature  No 3 H (water) problems  High He flow rate needed  Target oxidation by O 2 contamination in He env.  Radiation cooling:  High target temperature  Heat load on other equipment  To be evacuated

Summary on target optimization 11  Target optimized (1 st iteration) by using the  + yield below 70 mrad  2 nd iteration will be refined once a optimized focusing system will be available (higher angular acceptance)  Proposed configuration:  Length: 130 cm  Radius: 4-6 mm (8 mm possible)  No segmentation  Material:  =1.85 g/cm 3  Stresses and heat evacuation to be studied in detail as a function of the general design of target area July 2012P. Velten, M. Calviani (CERN)

Optimization of focusing system 12  Starting point design based on arXiv: v1 arXiv: v1  Optimization for different LAGUNA/LBNO scenarios  Based on the maximisation on the sensitivity on sin 2 (2  13 )  50 GeV primary beam (not 400 GeV) July 2012P. Velten, M. Calviani (CERN)  For the present first iteration of layout optimization  neutrino fluence and ND (or FD)  Next steps will take into account:  oscillatory behaviour (1 st and 2 nd peak)  interaction cross-section

Optimization of focusing system - configuration 13July 2012P. Velten, M. Calviani (CERN)  Horn & Reflector shape is fixed, taken from Andrea’s paper (NB: 50 GeV primary beam!)  2 mm thick Al sheet implemented in FLUKA (multiple scattering)  Shape optimization will be the topic of C. Lazaridis presentation  Optimization based on relative element positions & current d TH : target/horn relative distance I H : horn current d HR : horn/reflector relative distance I R : reflector current d TH d HR arXiv: v1arXiv: v1 conclusions: d TH = -30 cm I H = 200 kA d HR = 4 m I R = 200 kA

Target/Horn [d TH :I H ] optimization 14  Maximization of  fluence [ GeV] in ND  No reflector – assuming DP of L=400m, R=1.5m July 2012P. Velten, M. Calviani (CERN) Optimal horn configuration: d TH =0 cm I H =220 kA Technical considerations:  Target outside horn preferable (d TH < 0 cm)  Lower horn current is preferable Outside horn Inside horn touching Inside horn Outside horn

Horn/Reflector [d HR :I R ] optimization 15  Maximization of  fluence [ GeV] in ND  Use of optimal horn configuration from previous step July 2012P. Velten, M. Calviani (CERN) No  selection! Optimal reflector configuration: d HR =10 m I R =220 kA  Usefulness of the reflector confirmed (+40%  increase)

Horn/Reflector [d HR :I R ] optimization 16  To avoid any artefact from the  integration in the ND:   yield with  ≤  max – only very forward neutrinos (representative of FD) July 2012P. Velten, M. Calviani (CERN)  Optimization is confirmed within the present statistical uncertainties  Possibly lower current (~180 kA)

Iteration on horn optimization 17July 2012P. Velten, M. Calviani (CERN)  Check if after the reflector optimization the target/horn settings are still optimal (horn parameter sensitivity)  d TH & I H variation around the optimal value  ND  yield are still compatible within 10%

Focusing element effect in  + angular distribution 18July 2012P. Velten, M. Calviani (CERN) Reflector effect 4x

Decay pipe optimization 19July 2012P. Velten, M. Calviani (CERN) L DP = decay pipe length r DP = decay pipe radius  Reminder (CNGS DP)  L DP = 1 km  R DP = 1.75 m  Physics optimization of DP is complex, as several aspects need to be taken into account :   fluence in ND/FD – maximum   / e ratio – max. (sensitivity?)   ± fluence in the ND – minimum  (Cost…) – minimum (!)

Decay pipe optimization:  ND 20   fluence spectrum at ND (1 km)  Slightly shifted to lower energies for larger radius, longer DP July 2012P. Velten, M. Calviani (CERN)   fluence dependence at ND (1 km) 200 m 400 m 600 m r=150 cm 2x

Decay pipe optimization:  FD 21   fluence at FD (2300 km) July 2012P. Velten, M. Calviani (CERN)  With current optimizations: two oscillation maxima are not well matched  Wider energy distribution is needed  horn acceptance shall be increased!

 ± fluence in the ND 22  The  fluence in the ND is an issue which might contribute driving the HS design, DP length and the ND distance from TS  In iron, dE/dx|  ~1.6 GeV/m  16 GeV/10m  In molasses, dE/dX|  ~460 MeV/m  ~50 GeV/100m July 2012P. Velten, M. Calviani (CERN) 17.5 meters 5 m Fe C Hadron absorber ~15 m long Molasses assumed ~2.4 g/cm 3  HS in the present simulation setup:  5 m carbon core  12.5(17.5) m Fe shielding around  WANF: 4x4.5x36 m 3 + toroidal magnet (12 T*m, 10 m long, 6 m diameter)

 ± fluence in the ND 23July 2012P. Velten, M. Calviani (CERN) 350 m  At 500 m from TS  <10 5  /cm 2 /pulse  At 800m,  ~100  /cm 2 /pulse  Expect ~0.1  /cm 2 /pulse at ~1 km  Low statistics (massive biasing missing) ND 800 mND 500 m Worst case, averaging ~1 m along beam axis cm -2  Possible solutions:  Reduction of primary beam energy to 300/350 GeV?  Massive increase of DP Fe blocks (50/100 m Fe m molasse)  ND further away (much also deeper…)  TOSCA was at ~700 m from  pit (1800 m from TS) == 2.5  /m 2 /10 13 p +

Summary 24  Target  Ruled out the need for target segmentation (for  yield) -- mechanical considerations might require it  6 (or 8) mm radius target, 1.6 (or 2.1) mm 1  beam  Optimal configuration of the focusing system  A. Longhin shape (optimized for 50 GeV beam)  d TH =0 cm, I H = 220 kA & d HR =10 m, I R = 220 kA  Target outside the horn (for easier maintenance and handling)  Reduced distance target/reflector  compact design of TS  First look to the DP optimization  Assessment of a strategy/plan for optimization July 2012P. Velten, M. Calviani (CERN)

On-going work (1/2) 25  Study effect of “beam plug”:  Suppress high energy neutrino background  Will need to be (water?) cooled  Study effect of a focalizing “hadron hose” (NuMi)  Increase the neutrino event rate by ~30-50%  Randomization of the pion decay angles – FD/ND homogenization  Several technical issues to be addressed (Energy deposition? Durability? Stress? Powering issues?)  Reiterate on the studies with an optimized horn shape (see C. Lazaridis presentation) July 2012P. Velten, M. Calviani (CERN)

On-going work (2/2) 26  FLUKA modelling of target area based on a “chase” design (1 st iteration)  Energy deposition analysis (750 kW and 2 MW beam)  First radioprotection assessment of the area  Prompt dose rate around TS (access/electronics?)  Activation around the TS (+DP/HS)  Air activation  Hadron absorber initial design  Will have to be anyhow designed for a 2 MW beam  Do we need a significant reduction of  for the ND? July 2012P. Velten, M. Calviani (CERN)

Perspectives 27  After these first iterations:  Optimize to provide a wider neutrino spectrum in the low energy range,  Maximize the fluence at two oscillation maxima (~1.6±0.5 GeV and ~4±0.5 GeV)  Iteration with the beam/physics group will be needed to specify and address the optimal parameter for optimization  Concentrate efforts of different teams in an homogenized way July 2012P. Velten, M. Calviani (CERN)

28July 2012P. Velten, M. Calviani (CERN) Work is

29  Backup July 2012P. Velten, M. Calviani (CERN)

30July 2012P. Velten, M. Calviani (CERN) 600 m cm -2

31July 2012P. Velten, M. Calviani (CERN)

32July 2012P. Velten, M. Calviani (CERN) 4 mm radius 8 mm radius

Possible implementation 33  Initial configuration for preliminary evaluation July 2012P. Velten, M. Calviani (CERN) He container <30 meters targethorn reflector DP collimator (Fe) Concrete Air volume for structural support services ~3.5 m Fe Movable steel plates Movable concrete blocks ~5 m concrete Primary beam zone Decay pipe (DP) baffle Beam window Target station “surface” building & services

Some consideration on target area design 34  Guideline: try to reduce air activation  Avoid target area as big caverns where all equipment is installed close to personnel access  Use a 1 atm. He vessel to reduce 3 H and NO x  Avoid concrete blocks in the He vessel (T2K experience)  Handling to be performed from top – no need for local access  Radioprotection aspects  If surface location for the TS, watch out for radioactive air leakage (T2K experience)  Design should be conservative to take into account potential stricter 7 Be or 22 Na releases by local authorities July 2012P. Velten, M. Calviani (CERN)

CNGS HS 35July 2012P. Velten, M. Calviani (CERN)