On behalf of NNbarX Collaboration Yuri Kamyshkov/ University of T - PowerPoint PPT Presentation

Intensity Frontier Workshop  ANL  April 25 ‐ 27, 2013 On behalf of NNbarX Collaboration Yuri Kamyshkov/ University of T ennessee email: kamyshkov@utk.edu 1

 Observation of violation of Baryon number is one of the pillars needed for modern Cosmology and Particle Physics: ‐ it follows from the inflation (Dolgov & Zeldovich); ‐ required for explanation of BAU (Sakharov); ‐ present within SM, although at non ‐ observable level (‘t Hooft); ‐ motivated by BSM models (Georgi & Glashow, Pati &Salam, ...)   Proton decay  B = 1 and  B = 2 are complementary. n n 2

 Neutron ‐ antineutron transformation is natural in L ‐ R symmetric models with V(B - L) at the scales below 10 16 GeV scale where neutrino masses are also explained (Mohapatra & Marshak);  n n Observable together with new TeV ‐ scale color ‐ sextet scalars at LHC are predicted in the new scheme of Post ‐ Sphaleron Baryogenesis (Babu, Mohapatra).   n n Interesting theoretical discussions on R. Schrock and S. Nussinov (2002) K. Babu and R. Mohapatra et al. (> 2001) G. Dvali and G. Gabadadze (1999) J. Arnold et al. (2012) G. Durieux et al. (BLV ‐ 2013) http://www.mpi ‐ hd.mpg.de/BLV2013/ Z. Berezhiani (BLV ‐ 2013) 3

 - Scales of n n ( B L V in theory ) Non-SUSY Supersymmetric Seesaw for m  model Left-Right B  L , L  R Plank symmetric SUSY scale GUT GUT nn nn PDK  B  L 00 10 02 10 04 10 05 10 07 10 08 10 09 10 12 10 13 10 14 10 17 10 18 10 19 10 01 10 03 10 06 10 10 10 11 10 15 10 16 10 20 GeV 10    5        2 3  B L B L WK Dutta-Mimura-Mohapatra (2005) Goity, Sher (1994) Mohapatra & Marshak (1980) Observable effects at LHC Berezhiani; Babu et al. (2013) Experimental motivation! Berezhiani Bento (2005) large increase of sensitivity: Post ‐ Sphaleron Baryogenesis factor of  1,000 is possible Babu, Mohapatra, et al.(2013) compared to existing limit Low QG models nn LHC Dvali & Gabadadze (1999) GeV 00 10 02 10 03 10 04 10 05 10 06 10 07 10 01 10 08 10 09 10 10 10 11 10 12 10 4 Shrock & Nussinov (2002)

For experimental "quasifree conditions" 2 æ ö t ÷ ç ÷ when external fields are approx. 0 = ç n P ÷ ç  n ç ÷ t è ø and "observation" time ~ 0.1 s to 1 n t 0 s nn ⋅ 2 N t  sens itivi ty for fre e ne utrons  P 2 t = t ⋅  N t nn free  - 24 t = a < ⋅ is characteristic "oscillation" time [ 2 10 e V , as presently known] nn a Existing exp. limits are set by at ILL (free ) and by Super-K (bound n n ) - 25 - 26 a - Predictions of t heoret ical models: observable effect around ~ 1 0 10 eV 5

Previous state ‐ of ‐ the ‐ art n ‐ nbar search experiment with free neutrons Schematic layout of At ILL/Grenoble reactor in 89 ‐ 91 by Heidelberg ‐ ILL ‐ Padova ‐ Pavia Collaboration Heidelberg - ILL - Padova - Pavia nn search experiment M. Baldo-Ceolin et al., Z. Phys., C63 (1994) 409 at Grenoble 89-91 Top view of horizontal experiment (not to scale) Cold n-source 25  D2 fast n,  background 58 HFR @ ILL Bended n-guide Ni coated, 57 MW L ~ 63m, 6 x 12 cm 2 H53 n-beam . 11 ~1.7 10 n/s Focusing reflector 33.6 m Flight path 76 m < TOF> ~ 0.109 s No GeV back grou n ! d Detector: Tracking& Magnetically No candidates observed. n Calorimetry shielded n Discovery potential : Limit set for a year of running: 95 m vacuum tube n    t > ´ 8 2 9 0.86 10 N t s 15 10 . sec v ~ 700 m/s nn n = with L ~ 76 m and t 0.109 sec Measured limit : Annihilation  nn   - < ´ 18 measured P 1.606 8 6 10 7 10 . sec target  1.1m nn  E~1.8 GeV Beam dump 2 9 2 sensitivity: N t ⋅ = 1.5 ´ 10 s s 11  "ILL sensitivity unit" ~1.25 10 n/s 6

2 t = ´ t Free Neutron and Bound Neutrons R bound free NNbar Search Limits Comparison R was discussed by Ed Kearns Large improvement with free ‐ neutron experiments is possible Factor of 1,000 sensitivity increase Recent S ‐ K (2011) Post ‐ Sphaleron Baryogenesis limit based on 24 candidates Babu et al and 24.1 bkgr. intranuclear search exp. limits: Free neutron Super-K, Ultimate goal of new n-nbar search limit Soudan-2 search with free neutrons (ILL - 1994) Frejus, SNO 7

~ 1.3 GeV Yield is ~ 24 neutrons per GeV proton ~ 1.5  10 17 n/s/MW N. Mokhov, MARS simulations, FNAL, 2011 Spectrum of primary fast n from spallation target and from fission (Courtesy of Gary Russel). For target made of fissionable materials Potential source of the “fast ” (e.g. Th, DU) neutron yield can be factor background for n ‐ nbar that was ~ 2 higher (geometry dependent) non ‐ existent in the previous ILL experiment

9 Spallation Target in Project X

The Institut Laue Langevin 58 MW High Flux Reactor is optimized to serve many neutron beamlines Geoff Greene/UT 10

Spallation 1MW target at SNS Outer Reflector Plug Target Inflatable seal Core Vessel water cooled shielding p Core Vessel Multi-channel flange Tony Gabriel/UT/SNS 11

LD 2 A Configuration (B) F. Gallmeier/SNS 1 MW P 1 GeV Pb with LH 2 B D 2 O Configuration (A) G. Muhrer/LANL Preliminary C Fe B H 2 O Pb C ~ 1m 2 @ 1m A LD 2 D 2 O Energy spectrum of neutron currents in different models Initial UT model (C) L. Castellanos/UT 12

Conceptual Horizontal Baseline Configuration with elliptical focusing reflector (method proposed by us in 1995) D ~ 4 m Typical initial baseline parameters: MC Simulated sensitivity Nt 2 : Cold source configuration C Luminous source area, dia 30 cm 150 “ILL units” x years Annihilation target, dia 200 cm Reflector starts at 2 m Sensitivity and parameters are Reflector ends at 50 m subject of optimization by Monte ‐ Reflector semi ‐ minor axis 2.4 m Carlo including overall cost Distance to target 200 m Super ‐ mirror m=7 N ‐ nbar effect can be suppressed < 10  5 Pa Vacuum by weak magnetic field. Residual magnetic field < 1 nT 13

Independent sensitivity estimate by scaling from ILL experiment (Dave Baxter) Starting from Fundamental Physics beam line at SNS that is about similar to the cold beam in ILL experiment:  3 due to acceptance solid angle increase from m=3.5 to m=6  3 larger emission area of cold moderator  1.2 replacement target from Hg to Pb/Bi  2 more efficient moderator  6.9 flight path increase from 76m to 200m (some improvement factors are not included) __________________________________________________________  150 sensitivity increase factor  number of years For 3 years of running sensitivity can be ~ 450 of ILL units or  free = 1.8  10 9 s Sensitivity Nt 2 is a function of the performance of the source and several parameters of experiment which also can be defined and constrained by the cost factors. It is possible to envisage a configuration with larger sensitivity. The goal of our study is relate the configuration(s) with the cost by a parametric cost model. 14

Fermilab PAC recommendation sets for horizontal option a “minimal sensitivity goal” of ~ 30 or  free = 5  10 8 s 15

2 t = ´ t Free Neutron and Bound Neutrons R bound free NNbar Search Limits Comparison Large improvement with free ‐ neutron experiments is possible Factor of 1,000 sensitivity increase Recent S ‐ K (2011) Post ‐ Sphaleron Baryogenesis limit based on 24 candidates Babu et al and 24.1 bkgr. PX horizontal PX vertical 16

As compared to previous ILL/Grenoble experiment Existing ready ‐ to ‐ use technologies (within economical feasibility range) 1. Use super ‐ mirror reflector to intercept larger solid angle n’s from the source 2. Use advantages of the Project X for optimal design of the source/positioning 3. Parameters vs cost optimization Possible sensitivity improvement factor 450 or t free ~ 1.8 ´ 10 9 sec New technologies (R&D and cost ‐ impact studies are required) 1. Use vertical layout of experiment with flight path ~ 200 m 2. Use “4 p reflection source” with nano ‐ particle diamond reflectors 3. Use commercially improved high ‐ m reflecting mirrors 4. Use advanced colder cryogenic moderators 5. Understand possible limitations from radiation damage Additional sensitivity improvement factor  100 with t free up to 1 ´ 10 10 sec. 17

Exam ple of Vertical layout Focusing Super-m Reflector L ~ 20m Vertica l layout enab les use of the whole cold spectrum incl.UCN Vacuum Tube and = + 2 h v t gt 1 Mag. Shield 0 2 L ~ 100 m L~100 m Dia ~ 5 m dia ~ 4 m 2 2 2 ⋅ + ⋅ 105 m = 100 m/s 1 s 4.9 m/s 1 s ⋅ 2 ⋅ 2 2 105 m = 10 m/s 3.7 s+4.9 m/s 3.7 s 18

Further sensitivity improvement concept: dedicated spallation target with VCN-UCN converter (4  emission) (view along the beam) Heavy Metal Target: Pb, Bi, W, Ta Heavy Water R&D on reflector configuration , optimization , rad. stability, Solid D2 UCN and cost Converter ``` Liquid High-m Deuterium Super Mirror or diamond nanoparticles Graphite reflector Reflector Scheme being optimized Cold Neutrons 19 by simulations

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Colder moderator R&D at Indiana University / CEEM Fit to the Spectrum 13 MeV, CH4, 6K Super ‐ m acceptance tech. development Cold moderator tech. development Dave Baxter, Chen ‐ Yu Liu / Indiana U. 21