https://indico.cern.ch/event/807540/ n_TOF Target #3 Production Readiness Review History of Target #3 options and baselining M. Calviani (EN-STI) n_TOF Target #3 Project Leader https://indico.cern.ch/event/807540/ 29th May 2019 EDMS 2158302

M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302 Outline Summary of Target #3 design solutions Path towards the definition of the Target baseline Intermediate Engineering Design Review and follow-up Challenges and decision to focus on N2-cooled sliced Pb target Engineering Design Document and Project Costs 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Summary of Target #3 design evolution Over the course of the Project history, 5 design solutions have been identified and studies with a certain degree of details Sol4 Ti64-contained Pb core, ext. Pb mass Sol5 sliced Pb core, N2 cooled Sol3 Ta-cladded W core, ext. Pb mass Sol1 Bare Pb core Sol2 Ti64-contained Pb core Pb W Pb Ti-Pb Pb Ti-6Al-4V Pb Pb Discarded after PDR Discarded after PDR Baseline at IEDR Later discarded Baseline at PRR Backup at IEDR 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Solution #2 (core and vessel) Solution 2: water-cooled Ti-6Al-4V-cladded Pb core (monolithic) Solution discarded due to physics (Be stiffener reducing flux in EAR1) and technological reasons (complex to maintain good thermal contact) 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Solution #4 (core and vessel) Solution 4: water-cooled Ti64-cladded Pb core, embedded in an “air” cooled external Pb mass for physics reasons Solution judged sound by IEDR reviewers but quite complex to implement technically with significant reliability risks Complex mechanical assembly, cantilever core, complex N2 circulation in external mass 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302 Solution #5 Solution 5: N2-cooled Pb sliced target Technologically innovative, but appears the most appealing from a physics as well as technological perspective Operational simplification: no high-Z contaminated H2O, no ion-exchangers, etc. 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

NEW Target options at IEDR Solution 4 Ti64-contained pure Pb, water cooled, contained in a N2-cooled mass Solution 5 N2-cooled pure Pb slices 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

IEDR analysis of recommendations and follow-up Reviewers have highlighted the excellent quality of the presentations and work done, feedback provided in EDMS 2000974 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Project decision post IEDR & path towards IDR “Avoid unnecessary complexity”  remove mechanical complexity from the target pit and eventually move it out Re-optimization on physics performances for the target, balancing requirements from n_TOF Collaboration on EAR1 and EAR2 Focus on “neutron/gamma background” rather than on increasing power on target Contrary to previous requirements, the baseline was changed to keep the current average protons on target – 1.7*1012 p/s , maximizing the pulse intensity if feasible No manpower and budget to follow more than 1 solution  need to baseline Dedicate resources on the study and development of a nitrogen cooling station adapted to the Project needs Push in order to execute HiRadMat beam tests of both Solution #4 and #5 (October 2018) and a timely PIE on Solution #5 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Project decision post IEDR & path towards IDR Taking into account all pertinent factors the Project decided to: Go ahead with the detailed design and assessment of open points on the nitrogen cooled sliced Pb target (Solution #5) – baseline target Simplification of mechanical complexity in the target pit (inaccessible after installation) Stopping further developments of Solution #4 (Ti64- cladded Pb) given the complexity of the assembly and technical requirements similar to those of Solution #5 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Solution #5 IEDR suggestions From the review document (EDMS 2000974): Further study and define anti-creep geometry [required] in order to improve cooling even in case Pb creeping leads to clogging Assess the target assembly rigidity to limit vibrations and their consequences Optimize the cooling system and parameters (N2 flow rate and velocity in critical regions) as trade-off between cooling efficiency and induced vibrations or pressure losses Take into account nitrogen chemistry risks Reduce photon and high energy neutron streaming to experimental areas by using an additional lead wedge or tilted anti-creep plates, as proposed immediately after the review 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Project decision post IEDR & path towards IDR From July 2018 to November 2018 all Project resources dedicated to address the open points of Solution #5 highlighted by the IEDR Project organized an Internal Design Review (IDR) on 6th November 2018 in order to check the status No showstopper identified, leading to the go ahead for the detailed studies of the (now) baseline design (Solution #5) 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

n_TOF Collaboration feedback Baseline target design was presented to the n_TOF Collaboration at the Board meeting on 29th November 2019 Proposal was endorsed by the Collaboration Board Collaboration however requested a separated moderator circuit (EAR1 vs. EAR2) V. Vlachoudis 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Engineering Design Document A detailed design document has been prepared in order to summarize the design choices, studies, simulation, prototyping and beam tests Coverage of most of the aspects discussed at this review TOF-TAR-ES-0003 (EDMS 2154581), linked to the INDICO page 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Information of Project costs The Target #3 Project is fully financed by Accelerator Consolidation Project (ACC-CONS) Originally foreseen budget (~2014) was around 600 kCHF Current the Project is financed for a total 1.7 MCHF (M+P) Excluding costs for additional moderator (covered by the Collaboration) & other beam line related aspects, which will be covered by the STI n_TOF operational budget TOF-PM-MG-0002 (EDMS 2143839) is detailing the different budget sources – all looks ok at the moment 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302 Focus of the PRR In the last 6 months, Solution #5 (N2-cooled sliced Pb target) has been thoroughly analyzed, addressing most of the recommendation and suggestions from IEDR/IDR as well as actions from Project meetings Extensive CFD, including optimization of anti-creep plates (R. Ximenes) Thermo-mechanical simulations with coupled & sensitivity studies (R. Esposito) Summary of target vibration studies by external partner (R. Esposito) Detailed studies of the N2-cooling station (F. Dragoni) Significant prototyping to address feasibility (& costs) (M. Timmins) Beam irradiation tests (R. Esposito) The Project believes that this is a mature solution and ready to be built and operated 22 May 2019 M. Calviani - n_TOF Target #3 PRR Introduction - EDMS 2158302

Thanks a lot