ESS Based Super Beam for Lepton CP Violation Discovery

1. 1477 An ESS Based Super Beam for Lepton CP violation discoveryarXiv:1309.7022v2 [hep-ex] 14 Oct 2013Tord Ekelof, Uppsala Univerisity of behalf of the ESSνSB Collaboration ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

2. The ESS 2 GeV proton linac as proton driver for a neutrino Super Beam The European Spallation Source (ESS), which is being built in Lund, Sweden, will have a 2 GeV 5 MW (alternatively 2.5 GeV 5MW) superconductionlinac to produce 1.6x1016 protons on target/second* which is two orders of magnitude more than any other planned proton driver for a neutrino beam • T2HK – JPARK to HyperKamiokande 30 GeV, 0.75 MW -> • 1.6x1014 protons on target/second • LBNE – FNAL to Sanford Lab 60-120 GeV, 0.7 MW –> • 1.1x1014 protons on target/second First beams 2019 Full linac operation 2022 * = Power [W]/(Energy [eV]x1.6x10-19) ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

3. To measure low energy neutrinos a large water Cherenkov detector is required (low neutrino cross section) and sufficient (no inelastic event) • A “Hyperkamiokande” type detector to study; • Neutrinos from accelerators (Super Beam) • but also • Supernovae neutrinos (burst + "relics"), • Solar Neutrinos, • Atmospheric neutrinos, • Geoneutrinos • Proton decay up to ~1035 years life time. • All these other measurements require the detector to be shielded by ~1000 m rock from cosmic ray muons • The MEMPHYS detector of the FP7 LAGUNA project; • Fiducial mass: 440 kt in 3 cylinders 65x65 m • Readout: 3x81k 12” PMTs, 30% geom. cover. • Order of magnitudecost : 700 MEuro ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University 3

4. The depth and distance from ESS/ Lund of different mines in Scandinavia ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

5. Which is the optimal base line for the ESS SuperBeam for CP violation discovery? The fraction of the full δCP range 0o-360o within which CP violation can be discovered as function of the baseline length in km for proton linac energies 2, 2.5 and GeV. The lower (upper) curves are for CP violation discovery at 5σ (3σ ) significance. Enrique Fernandez Garpenberg Znkgruvan ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

6. Maximum CP violation sensitivity at the 2nd oscillation maximum With the newly measured high value of ca 0.1 for sin22θ13 the CP angle sensitivity is significantly higher at the second νμ→νe oscillation maximum than at the first. With low energy neutrinos the neutrino detector can be placed at the second oscillation maximum. All other earlier planned experiments have higher neutrino energy and their detector at the first oscillations maximum CP violation angle 5000 4000 Proton energy Base line 3000 Number of unosillated detected events νμ→νe oscillation probability 2000 1000 0 2nd osc max 1st osc max Enrique Fernandez Neutrino energy ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

7. Number of signal and background events for electron neutrinos and anti-neutrinos for 2+8 GeV run as detected in a MEMPHYS type detector after 2 years of neutrino running (left) plus 8 years of antineutrino running (right) with a baseline length of 540 km and 2.5 GeV protons The νμ->νe oscillation signal is in blue. Backgrounds in other colors are low because of the low energy. neutrinos anti-neutrinos 7 ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

8. How can the ESS linac be used as a proton driver for a neutrino Super Beam, maintaining spallation neutron production unchanged? Proposal; By rising the linac 3-ms-pulse frequency from 14 Hz to 28 Hz, thereby doubling the average RF power from 5 MW to 10 MW This will allow for that 14 linac pulses per second be used for neutron physics and 14 pulses for neutrino physics. For this it will be necessary to double the output power from the linac RF sources and the linac cooling capacity. Modulators, amplifiers and power transfer equipment should be designed for the doubled average power of the linac already during the build-up phase. ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

9. Test of operation a RF power source at 28 Hz A prototype 352 MHz spoke cavity for the ESS linac will be tested in the FREIA Laboratory at Uppsala University already as from July 2014 in a cryostat at 14 Hz pulse frequency and at the full instantaneous power required for ESS proton acceleration, which is 350 kW. For the generation of the 352 MHz power both a tetrode amplifier and a solid state amplifier will be tried out. As part of the EUROSB project, the amplifier pulse frequency will be raised to 28 Hz, thus doubling the average power to the cavity. The influence of this higher power on the operation of the cavity and on the capacity to cool the cavity itself and, in particular, its RF coupler will be studied. Lay-out of the 352 MHz RF source, wave guides and test cryostat in the FREIA hall ESS Spoke 352 MHz Accelerating Cavity ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

10. The Target A challenging part of this project is the target to be hit by the 5 MW proton beam to produce the pions needed for the neutrino beam production. The use of classical monolithic solid targets is impossible for this application because of the absence of efficient cooling. One design which is under investigation is a packed bed of titanium spheres cooled with cold helium gas. It needs to be investigated whether the pulsed beam will generate vibrations in the spheres, which could be transmitted to the packed bed container and beam windows and cause degradation of the spheres where they are in contact with each other. Tests of such a target are planned using the HiRadMat high intensity proton irradiation facility at CERN. ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

11. The Neutrino Horn A key element for generating a neutrino beam is the hadron collector, also called neutrino horn, used to focus in the forward direction the charged pions produced in the proton-target collisions A pulsed power supply able of providing the very high current (~350 kA) to be circulated inside the horn at the required pulse rate has not been produced so far and thus needs to be prototyped. Furthermore, the time duration of this high current pulse can only be of a few microsecond to not overheat the horn. This implies that the ESS pulse length of ca 3 milliseconds has to be shortened by ca 2000 times using a storage ring in which the whole 3 ms long pulse is accumulated by multi(2000)-turn injection and then ejected in one turn. To obtain a 1.5 μs pulse the ring should have a 450 m circumference. ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

12. Target StationGeneral Layout Shield Blocks Horn Support Module Split Proton Beam Horns and Targets Collimators Decay Volume (He, 25 m) Neutrino Beam Direction Beam Dump ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University M. Dracos 12

13. H-accleration, injection and compression During the 3 ms long period of injection in the storage ring the large stored positive charge will repel the successively arriving negatively positive protons. To alleviate this problem one must inject H- ions and strip off the electrons from the H- ions at the moment when they enter the stored circulating beam. The proposed plan for simultaneous H- acceleration is to have one 3 ms long 50 mA H- pulse accelerated in the 70 ms long gap between to proton (H+) pulses. The large stored charge also causes space charge problems and beam blow-up in the compressor storage ring, which can be alleviated by dividing up the ring on four rings. This is a trick already used for the CERN PS Booster ring. The 4 rings of the CERN PS Booster ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

14. H- source Stripping There exist sources that could give the required performance for EUROSB ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University Courtesy: J. Lettry 14

15. Lay-out of ESS neutrino beam p Neutron spallation target ESS linac H- Neutrino beam Target/horn station Accumulator ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University 15

16. ESS overall schedule ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

17. Gruvsjöschaktet Nytt schakt Garpenberg Mine Distance from ESS Lund 540 km Depth 1232 m Truck access tunnels Two ore hoist shafts SDn / 2012 A new ore hoist schaft is planned to be ready i 1 year, leaving the two existing shafts free for other uses Granite drill cores ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

18. Zinkgruvan mine Distance from ESS Lund 360 km Depth 1200 m Access tunnel 15 km Ore hoist shaft 7m/s 20 tons Personnel hoist shaft New ore volume 2 km long tunnel planned for new ore volume – 3 Memphys cavities could be built adjacent to this tunnel. Extension of access tunnel and second hoist shaft needed. ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University 18

19. Currently we are investigating the possibilities offered by the North shaft and decline of the Garpenberg mineThe construction of this shaft and decline started in the 1960s. The current shaft depth of 830 m was reached in 1994 and the depth of the decline (=descending truck tunnel, cross section 5mx6m), which was 1000 m in 1998, has later been extended to 1230 m depth. In 2012 300 000 tons (=110 000 m3) of ore was transported with trucks on the decline up to the shaft hoist at 830 m depth and hoisted up to the ground level so 550 000 m3 can be hoised in 5 years.The hoist, shaft and head-frame (=hoist surface tower) will no longer be used for mining as from end of 2014. To preserve them will require their maintenance. ESSnuSB presentation at NNN2013 TordEkelöf Uppsala University

20. The dominating limestone and dolomite rock in the ca 2 km broad and 10 km long syncline (~area) of the mine is not suitable for the excavation of the very large MEMPHYS/HyperK type of detector caverns. However, the syncline is surrounded by granite which is of sufficient strength to allow the safe construction of large caverns. Bore holes have been made out to the granite zone and recent rock strength measurements of 18 granite bore core samples collected (see photographs below ) have yielded a mean value of the uniaxial compressive strength of 206 MPa (cf. 232 Mpa at Pyhäsalmi mine).The rock stress at 880 m depth has previously been measured. The main component of the stress is horizontal and directed perpendicularly to the syncline, i.e. to the north-west. The rock stress magnitude is about 40 MPa (cf. 52 MPa at Pyhäsalmi mine at 900 m) which is a little less than twice the vertical stress component that is induced by the gravitation. ESSnuSB presentation at NNN2013 TordEkelöf Uppsala University

21. Performance calculations for ESSνSB based on GLOBUS simulations The systematicerrorsused are those given in the Snowmass reference; Systematicuncertainties in long-baseline neutrino oscillations for largeθ13 Pilar Coloma, Patrick Huber, Joachim Kopp, Walter Winter arXiv:1209.5973 [hep-ph] PhysRevD.87.033004 ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

22. CPV Discovery Performance for Future SB projects, MH unknown, Snowmass comparison • IDS-NF Neutrino Factory • NuMAX are: 10 kton magnetized LAr detector, Baseline is 1300 km, and the parent muon energy is 5 GeV • LBNO100: 100 kt LAr, 0.8 MW, • 2300 km • Hyper-K: 3+7 years, 0.75 MW, • 500 kt WC • LBNE-Full 34 kt, 0.72 MW, 5/5 years • ~ 250 MW*kt*yrs. • LBNE-PX 34 kt, 2.2 MW, 5/5 years ~750 MW*kt*yrs. • ESSnuSB, in the figure called EUROSB: 2+8 years, 5 MW, 500 kt WC (2.5 GeV, 360 (upper)/540 km (lower)) • 2020 currently running experiments by 2020 ESS 2.5 GeV Pilar Coloma ESSnuSB presentation at NNN2013 TordEkelöf Uppsala University

23. The fraction of all possible true values of δCP as a function of the 1 σ error in the measurement of δCP . A CP fraction of 1 implies that this precision will be reached for all possible CP phases, wheras a CP fraction of 0 means that there is only one value of δCP for which the measurement will have that precision. ESSνSB ESS 2.5 GeV Pilar Coloma ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

24. Coarse cost estimateUnit: Billion Euro (109 Euro)Upgrading the ESS accelerator 0.1 Compressor ring 0.2 Target station 0.2 Detector 0.7 The ESS linac 0.6 --------------------------------------------------Green field project cost 1.8Using the ESS linac -0.6--------------------------------------------------ESS neutrino Super beam project 1.2 ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

25. The ESSνSB Authors and Institutions E. Baussan,m M. Blennow,l M. Bogomilov,k E. Bouquerel,m J. Cederkall,f P. Christiansen,f P. Coloma,b P. Cupial,e H. Danared,g C. Densham,c M. Dracos,m; T. Ekelöf,n; M. Eshraqi,g E. Fernandez Martinez,h G. Gaudiot,m R. Hall-Wilton,g J.-P. Koutchouk,n,d M. Lindroos,g R. Matev,k D. McGinnis,g M. Mezzetto,j R. Miyamoto,g L. Mosca,i T. Ohlsson,l H. Öhman,n F. Osswald,m S. Peggs,g P. Poussot,m R. Ruber,n J.Y. Tang,a R. Tsenov,k G. Vankova-Kirilova,k N. Vassilopoulos,m E. Wildner,d and J. Wurtz.m a Institute of High Energy Physics, CAS, Beijing 100049, China. b Center for Neutrino Physics, Virginia Tech, Blacksburg, VA 24061, USA. c STFC Rutherford Appleton Laboratory, OX11 0QX Didcot, UK. d CERN, CH-1211, Geneva 23, Switzerland. e AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow, Poland. f Department of Physics, Lund University, Box 118, SE{221 00 Lund, Sweden. g European Spallation Source, ESS AB, P.O Box 176, SE-221 00 Lund, Sweden. h Dpto. de Fsica Teorica and Instituto de Fsica Teorica UAM/CSIC, Universidad Autonoma de Madrid, Cantoblanco E-28049 Madrid, Spain. i Laboratoire Souterrain de Modane, F-73500 Modane, France. j JINFN Sezione di Padova, 35131 Padova, Italy. k Department of Atomic physics, St. Kliment Ohridski University of Soa, Soa, Bulgaria. l Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Tech- nlogy, AlbaNova University Center, SE-106 91 Stockholm, Sweden. m IPHC, Universite de Strasbourg, CNRS/IN2P3, F-67037 Strasbourg, France n Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden New collaborators are most welcome to join in! ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

26. CONCLUSIONSWe propose the utilisation of the ESS linac to build a physicscompetitive and cost effective world leading neutrino Super Beam facility for neutrino CP violation discovery. The technical feasibility of this project are being studied in detail with computer simulations and prototype tests. There is a strong synergy between the use of the ESS linac for the production of spallation neutrons and a low energy neutrino Super Beam .The MEMPHYS type neutrino detector will also enable a rich variety of other measurements involving atmospheric and cosmic neutrinos ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

27. A discovery of CP violation in the leptonic sector will have strong cosmological implications opening new possibilities to comprehend the matter/anti-matter asymmetry in Universe. Preliminary studies give very promising results compared to other neutrino facility proposals in Europe and elsewhere in the world. arXiv:1309.7022v2 [hep-ex] 14 Oct 2013 ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

28. Back-up slides ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

29. Hyper-Kamiokande Physics Opportunities: Exploring CP Violation with the Upgraded JPARC Beam 36 % δCP coverage 55 % δCP coverage ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University 29

30. Systematic uncertainties in long-baseline neutrino oscillations for large $θ_{13}$Pilar Coloma, Patrick Huber, Joachim Kopp, Walter Winter(Submitted on 26 Sep 2012)We study the physics potential of future long-baseline neutrino oscillation experiments at large $\theta_{13}$, focusing especially on systematic uncertainties. We discuss superbeams, \bbeams, and neutrino factories, and for the first time compare these experiments on an equal footing with respect to systematic errors. We explicitly simulate near detectors for all experiments, we use the same implementation of systematic uncertainties for all experiments, and we fully correlate the uncertainties among detectors, oscillation channels, and beam polarizations as appropriate. As our primary performance indicator, we use the achievable precision in the measurement of the CP violating phase $\deltacp$. We find that a neutrino factory is the only instrument that can measure $\deltacp$ with a precision similar to that of its quark sector counterpart. All neutrino beams operating at peak energies $\gtrsim 2$ GeV are quite robust with respect to systematic uncertainties, whereas especially \bbeams and \thk suffer from large cross section uncertainties in the quasi-elastic regime, combined with their inability to measure the appearance signal cross sections at the near detector. A noteworthy exception is the combination of a $\gamma=100$ \bbeam with an \spl-based superbeam, in which all relevant cross sections can be measured in a self-consistent way. This provides a performance, second only to the neutrino factory. For other superbeam experiments such as \lbno and the setups studied in the context of the \lbne reconfiguration effort, statistics turns out to be the bottleneck. In almost all cases, the near detector is not critical to control systematics since the combined fit of appearance and disappearance data already constrains the impact of systematics to be small provided that the three active flavor oscillation framework is valid. ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

31. Comparison of the performance between proposed Future Long Base Line Neutrino Super Beam Experiments Proposal detector dist. power proton years acronym (km) vol. (kt)/type (km) (MW) energy (GeV) ν/ν¯ ------------------------------------------------------------------------------------- ESSνSB-360 500/WC 360 5 2.0 2/8 ESSνSB-540 500/WC 560 5 2.0 2/8 Hyper-K 560/WC 295 1.66 30 1.3/3.5 LBNE-Full 34/LAr 1290 0.72 120 5/5 LBNE-PX 34/LAr 1290 2.2 120 5/5 LBNO-100 100/LAr 2300 2.2 50 5/5 IDS-NF 100/LAr 2000 4 10 (for muons) 5/5 NuMAX 10/LAr (magn.) 1300 1 5 (for muons) 5/5 Systematic uncertainties in long-baseline neutrino oscillations for large θ13 Pilar Coloma, Patrick Huber, Joachim Kopp, Walter Winter arXiv:1209.5973 [hep-ph] PhysRevD.87.033004 ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

32. 2.5 GeV proton energy 540 km base line Garpenberg mine 360 km base line Zinkgruvan mine ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

33. 2.0 GeV proton energy 540 km base line Garpenberg mine 360 km base line Zinkgruvan mine ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

34. The signifiance in terms of number of standard deviations with which CP violation could be discovered for δCP-values from -180 to +180 degrees for 2.0 GeV protons ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

35. The signicance in terms of number of standard deviations with which CP violationcan be discovered as function of the fraction of the full δCP range for different proton energies and base lines ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

36. The resolution with which the δCP angle can be measured as function of δCP for different energies and base lines ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

37. Mass hierarchy determination for different base lines The significance in mass hierarchy determination as function of δCPfor different base line lengths (Enrique Fernandez) Measurements with atmospheric neutrinos will further improve this performance ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

38. CPV Discovery Performance for Future SB projects, MH unknown, Snowmass comparison • IDS-NF Neutrino Factory • NuMAX are: 10 kton magnetized LAr • detector, Baseline is 1300 km, and the • parent muon energy is 5 GeV • LBNO100: 100 ktLAr, 0.8 MW, • 2300 km • Hyper-K: 3+7 years, 0.75 MW, • 500 kt WC • LBNE-Full 34 kt, 0.72 MW, 5/5 years • ~ 250 MW*kt*yrs. • LBNE-PX 34 kt, 2.2 MW, 5/5 years • ~750 MW*kt*yrs. • EUROSB: 2+8 years, 5 MW, 500 kt • WC (2.0 GeV, 360 (upper)/540 km • (lower)) • 2020 currently running experiments by • 2020 ESS 2.0 GeV Pilar Coloma ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

39. Effect of systematic errors, MH unknown Points – no systematic errors Blue line –ESSνSB group estimated systematic errors (5% for signal and 10% for background) Red line – Snowmass estimated systematic errors for ESSνSB for comparison of performance of different experiments Ref P. Coloma et al. Phys.Rev. D87.033004 360 km 2 GeV ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University

40. The fraction of all possible true values of δCP as a function of the 1 σ error in the measurement of δCP . A CP fraction of 1 implies that this precision will be reached for all possible CP phases, wheras a CP fraction of 0 means that there is only one value of δCP for which the measurement will have that precision. ESS 2.0 GeV Pilar Coloma ESSnuSB presentation at NNN2013 Tord Ekelöf Uppsala University