1. 1 1477 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelof, Uppsala University 1 ESSnu interests 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University

2. The ESSnuSB Collaboration 40 participating scientists from 12 institutes in Sweden, France, Spain, England, Switzerland, Italy, Poland, Bulgaria and Greece The ESSnuSB Proposal published in Nuclear Physics B885(2014)127-149 Also available as arXiv:1309.7022 2 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 2016-07-10

3. The current efforts in the ESSnuSB Design Study are focused on: 1. The ESS linac power upgrade and acceleration of H - pulses 2. The accumulator ring design and beam dynamics 3. The neutrino target and horn 4. Rock engineering prospection and studies for the excavation of large the required cavern(s) in the Garpenberg-mine granite-zones As to the Far Detector photodetector optimization and the Near Detector(s) designs we are very interested by the results being obtained and presented by the Super-K/ T2K / Hyper-K development projects. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 3

4. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 4 2016-05-20 RECFA Meeting Lund 20 May 2016 Tord Ekelöf Uppsala University 4 ESS construction site February 2016 and ESSnuSB ν p n H-H-

5. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 5 The ESS LINAC tunnel now completed

6. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 6 For the warm low-energy part of the ESS linac and the medium energy Elliptical-cavities part, ESS is planning to use modulators of the modular klystron modulator type which can be run at 28 Hz at double power by adding a capacitor charger-unit at the input. For the high energy elliptical Cavities IOTs will be used which by design can operate CW. Preparing the ESS linac for operation at 10 MW with a 8% duty cycle and 28 Hz pulsing For the medium-beta elliptical-cavity part ESS is planning to use tetrodes. Thales has developed a new screen grid with graded wire thickness such that the heating is evenly distributed over the hight of the screen grid, thereby making operation at 10 % duty cycle possible.

7. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 7 The picture shows the cryostat and test bunker at the FREIA Lab in Uppsala where a first prototype of the ESS 352 MHz spoke accelerating cavity is currently under test at 14 Hz and later on will be tested at 28 Hz. Modulators for the high beta part of the linac will also be tested at 28 Hz. FREIA

8. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 8 Required modifications of the ESS accelerator architecture for ESSnuSB F. Gerigk and E. Montesinos CERN, Geneva, Switzerland Abstract This report is a summary of major modifications to the ESS nominal linac layout, which are needed to enable the operation of the ESS linac as 5 MW proton driver for the ESSnuSB initiative in addition to its regular operation as 5 MW ESS proton source. A draft costing is also provided using extrapolations from the ESS official cost numbers and values, which are familiar to the authors. This assessment was made during a visit by F Gerigk (CERN) and E Montesinos (CERN) to ESS on 1 – 2 June 2016 together with staff members of ESS. The visit took place on the initiative and with the support of the University of Uppsala (Tord Ekelöf). We are very grateful to Mamad Eshraqi who organized our visit at ESS and who made it possible for us to discuss with the relevant ESS experts and work package leaders. In the following we start with the charge for the review, the considered ESSnuSB scenarios, an executive summary and then a detailed list of findings, comments and recommendations ordered by subject. Contents 1The charge for the assessment 2Scenarios for ESSnuSB 3Executive Summary 4Detailed upgrade measures 4.1Civil engineering & integration 4.2Electrical network 4.3RF sources, RF distribution & modulators 4.4Cryogenics (plant + distribution) 4.5Water cooling 4.6Superconducting cavities, couplers & cryomodules 4.7Beam physics 5. Appendix 1: Visit time table 6. Appendix 2: Indicative costing of the upgrade CERN-ACC-NOTE-2016-0050 8 July 2016 Quotation from “Executive Summary: “No show stoppers have been identified for a possible future addition of the capability of a 5 MW H- beam to the 5 MW H+ beam of the ESS linac built as presently foreseen. Its additional cost is roughly estimated at 250 MEuros.”

9. OVERVIEW OF THE ESSNUSB ACCUMULATOR RING M. Olvegård, T. Ekelöf, Uppsala University, Sweden E. Benedetto, M. Cieslak-Kowalska, M. Martini, H. Schönauer, E. Wildner, CERN, Geneva, Switzerland Abstract The European Spallation Source (ESS) is a research center based on the world’s most powerful proton driver, 2.0 GeV, 5 MW on target, currently under construction in Lund. With an increased pulse frequency, the ESS linac could deliver additional beam pulses to a neutrino target, thus giving an excellent opportunity to produce a high-performance ESS neutrino Super-Beam (ESSnuSB). The focusing system surrounding the neutrino target requires short proton pulses. An accumulator ring and acceleration of an H ̄ beam in the linac for charge-exchange injection into the accumulator could provide such short pulses. In this paper we present an overview of the work with optimizing the accumulator design and the challenges of injecting and storing 1.1·10 15 protons per pulse from the linac. In particular, particle tracking simulations with space charge will be described Paper presented at the 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams, HB2016, hosted by the ESS in Malmö, Sweden, 2016 July 3-8. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 9

10. 10 Mitigation of high power effects in the neutrino production target – studies from EUROnu being continued Packed bed canister in symmetrical transverse flow configuration (titanium alloy spheres) Four-target/horn system to mitigate the high proton beam power (5 MW) and rate (70 Hz) Target inside the horn Downstream of the accumulator ring the beam pulses are distributed in sequence on the four targets

11. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 11 MUON PRODUCTION VIA THE ESSνSB PROJECT E. Bouquerel*, E. Baussan, M. Dracos, IPHC, UNISTRA, CNRS, 23 rue du Loess, 67200,, Strasbourg, France N. Vassilopoulos, Institute of High Energy Physics, CAS, Beijing 100049, China on the behalf of the ESSνSB project Abstract ESSnuSB plans to produce very intense neutrino beams using the protons from the ESS linac (5 MW, 2 GeV) and a 4-targets horn system. In the ESSnuSB proposed facility a copious number of muons will also be produced. These muons could be used by a future Neutrino Factory to stud yCP violation in the leptonic sector but also to study neutrino cross-sections. They could also be used to feed a future muon collider. The feasibility and the issues of extracting the intense muon beam produced together with neutrinos are discussed. Proceedings of IPAC2016, Busan, Korea Pre-Release Snapshot 19-May-2016 00:00 UTC THPMB001

12. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 12 Muons of average energy ca 0.5 GeV at the level of the beam dump (per proton) y (cm) x (cm) 4.2x10 20 μ/year (16.3x10 20 for 4 m 2 ) 4.1x10 20 μ/year ESS neutrino and muons facility 12 2.7x10 23 p.o.t/year ESS neutrino and muon facility ESS proton driver  decay  or    Decay channel or ring  Decay channel or ring Front end Cooling Storage ring Storage ring RCS acceleration RCS acceleration Collider ring Collider ring RLA acceleration RLA acceleration Neutrons to ESS Protons dump  Test Facility Short Baseline Detector Long Baseline Detector Short Baseline Detector Long Baseline Detector   or    +  e e +   Muon Collider nuSTORM Neutrino Factory ESS nu SB Accumulator Ref. M.Darcos and J.P. Delahaye Target Station Target 25 m long decay tunnel Proton beam

13. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 13 ESS-NUSTORM: a tentative layout

14. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 14 Rock engineering prospection and studies in the Garpenberg-mine granite-zones Distance from ESS Lund 540 km Depth 1232 m Truck access tunnels One hoist shaft free to use by ESSnuSB S D n / 20 12 Gru vsjö scha ktet N yt t sc ha kt Granite drill cores

15. 1. Investigation of new photo-sensors, in particular HPD and LAPPD 2. The development of ND280, in particular WAGASHI and BabyMIND for particle identification 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 15 There are four investigation areas of T2K/Hyper-K which are of interest for ESSnuSB

16. 3. EGADS and TITUS, in particular for Gadolinium-doping 4. NuPRISM, in particular for neutrino energy determination We follow this comprehensive program with great interest and hope to be able to make some contribution to it in future. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 16

17. Similarities and differences between Hyper-K and ESSnuSB 1. ESSnuSSB will measure at the second oscillation maximum where the sensitivity to systematic errors is ca 3 times smaller than at the first where Hyper-K will measure. 2. ESSnuSB has a neutrino mean energy of ca 400 MeV which is lower than the T2K and Hyper-K neutrino mean energy og ca 600 MeV. ESSnuSB therefore has somewhat lower backgrounds from neutrino resonace scattering (RS), neutrino deep inelastic scattering (DIS) and K-decay electron-neutrinos compared to T2K and Hyper-K. In any case, also ESSnuSB needs to study and determine these backgrounds as accurately as possible. And we are particularly interested in optimizing the design of the near detector that should monitor the neutrino flux and to measure the electron neutrino cross-sections on water. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 17

18. 18 Θ 13 =8.73 o 1 st osc. max 2 nd osc. max 3 rd osc. max ESSnuSB was designed for the larger value of Θ 13 CP violation discovery sensitivity is significantly larger at the second oscillation maximum as compared to the first Garpenberg 18 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 2016-07-10 3σ3σ 5σ5σ

19. Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 19 Systematic errors Phys. Rev. D 87 (2013) 3, 033004 [arXiv:1209.5973 [hep-ph]]

20. 20 The sensitivity of the neutrino energy distribution to δ CP Hyper-K first maximum LBNE/DUNE first maximum ESSnuSB second maximum Relative difference in counts at maximum between δ CP = 3π/2 and π/2 : 430/275 = 1.6 150/100 = 1.5 105/22 = 4.8 Hyper-K Events/100MeV Hyper-K 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University

21. From Stephen Parke/ FNAL; “Neutrinos: Theory and Phenomenology” arXiv:1310.5992v1 [hep-ph] 22 Oct2013, page 12; “At the first oscillation maximum (OM), as is in the running experiments, T2K and NOνA and possible future experiments HyperK and LBNE experiments, the vacuum asymmetry is given by A ~ 0.30 *sin δ at Δ 31 =π/2 which implies that P(ν ̅ μ →ν ̅ e ) is between 1/2 and 2 times P(ν μ →ν e ). Whereas at the second oscillation maximum, the vacuum asymmetry is A ~ 0.75 *sin δ at Δ 31 =3π/2 which implies that P(ν ̅ μ →ν ̅ e ) is between 1/7 and 7 times P(ν μ →ν e ). So that experiments at the second oscillation maximum, like ESSnuSB [15], have a significantly larger divergence between the neutrino and anti-neutrino channels.” 21 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 2016-07-10

22. Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 22 The ESSnuSB performance, the accumulator ring studies and some near detector simulations are reported in an ESSnuSB progress paper to appear in July 2016 in Hindawi Publishing Corporation Advances in High Energy Physics Article ID 873567: The Opportunity Offered by the ESSnuSB Project to Exploit the Larger Leptonic CP Violation Signal at the Second Oscillation Maximum and the Requirements of This Project on the ESS Accelerator Complex E. Wildner, 1 E. Baussan, 2 M. Blennow, 3 M. Bogomilov, 4 A. Burgman, 5 E. Bouquerel, 2 C. Carlile, 6 J. Cederkäll, 5 P. Christiansen, 5 P. Cupial, 7 H. Danared, 8 M. Dracos, 2 T. Ekelöf, 6 M. Eshraqi, 8 R. Hall-Wilton, 8 J.-P. Koutchouk, 1,6 M. Lindroos, 8 M. Martini, 1 R. Matev, 4 D. McGinnis, 8 R. Miyamoto, 8 T. Ohlsson, 3 H. Öhman, 6 M. Olvegård, 6 R. Ruber, 6 H. Schönauer,1 J. Y. Tang, 9 R. Tsenov, 4 G. Vankova-Kirilova, 4 and N. Vassilopoulos 9,,CERN, 1211 Geneva 23, Switzerland2I PHC, Universite´ de Strasbourg, CNRS/IN2P3, 67037 Strasbourg, France3 Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden 4Department of Atomic Physics, St. Kliment Ohridski University of Sofia, 1164 Sofia, Bulgaria 5Department of Physics, Lund University, P.O. Box 118, 221 00 Lund, Sweden 6Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden 7 AGH University of Science and Technology, Aleja Mickiewicza 30, 30-059 Krakow, Poland 8 European Spallation Source, ESS ERIC, P.O. Box 176, 221 00 Lund, Sweden Institute of High Energy Physics, CAS, Beijing 100049, China

23. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 23 The QE, RES and DIS neutrino cross-sections at the mean neutrino energies of ESSnuSB (0.4 GeV, left arrow) and of Hyper-K (0.6 GeV, right arrow) neutrinos antineutrino s

24. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 24 COST Action EuroNuNet In October 2015 an application for a EU COST Action CA15139 “EuroNuNet” was approved. Present participants: Bulgaria, Croatia, France, Greece, Italy, Poland, Spain, Sweden, Switzerland and United Kingdom The application was accepted with 57 out of 65 marks. Quotation from the evaluation report with reference to ESSnuSB: “The main strengths are that the present project is unique in Europe, and at this moment there are no other similar plans in the continent and it is building on a number of previous European projects. Only two other, similar projects exist in the USA and Japan. In addition, the project is not only complementary to the projects in the USA and Japan but clearly competitive with them, because the infrastructure proposed, which plans to locate the detector at the second neutrino oscillation maximum, will provide a much better and larger accuracy than the other two projects.”

25. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 25 One regards the additions to, and modification of, the ND280 TPCs. The TPC read-out electronics sits in front of the electromagnetic calorimeters and therefore needs to have as little mass as possible. The Lund ALICE group in Sweden has developed a very compact and lightweight TPC read-out chip ALTRO, now being further developed as the SALTRO16 chip, that could be of some interest when considering a new read-out electronics for the ND280 TPC read-out. Some very first ideas on how to contribute to the T2K/ Hyper-K development program have been discussed. The ALTRO chip

26. The BabyMIND detector is currently being assembled at CERN and will be tested in a CERN PS beam in May 2017. We see this as an interesting muon identification detector and are interested to participate in the test runs at CERN. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 26 These are some first ideas for participation that we would like to pursue. We would also like to see if there are more ways to collaborate and would welcome further ideas for this to be discussed BabyMIND module layout

27. Concluding remarks ESSnuSB actively studies the upgrade of the ESS linac including the addition of a compressor ring with the aim of providing 5 MW of 2 GeV protons to produce a exceptionally intense neutrino beam allowing to take data at the second oscillation maximum. There are also rock engineering studies of the Garpenberg mine being pursued for the design of the Far Detector cavern. ESSnuSB is following with great interest the comprehensive photodetector and near detectors development program of T2K/Hyper-K and expresses an interests in contributing to this program. For this, contributions of mutual interest to ESSnuSB and T2K/Hyper-K should be identified. Some first ideas regarding the ND280 TPC read-out electronics and the BabyMIND tests in a CERN beam have been discussed. We would like to pursue further discussion with T2K/Hyper-K of these ideas and also any other new ideas. 2016-07-10 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 27

28. Thanks for your attention 28 Hyper-K Collaboration Meeting at QMU London 10 July 2016 Tord Ekelöf Uppsala University 2016-07-10