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

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

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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

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Yuri Kamyshkov/ University of T ennessee email: kamyshkov@utk.edu

Intensity Frontier Workshop  ANL  April 25‐27, 2013

1

On behalf of NNbarX Collaboration

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 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 

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 Neutron‐antineutron transformation is natural in L‐R symmetric models with V(B-L) at the scales below 1016 GeV scale where neutrino masses are also explained (Mohapatra & Marshak); Observable together with new TeV‐scale color‐sextet scalars at LHC are predicted in the new scheme of Post‐Sphaleron Baryogenesis (Babu, Mohapatra).  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)

n n  n n 

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10

00 10 0110 02 10 03 10 04 10 05 10 06 10 07 10 0810 0910 1010 1110 12

LHC

nn

Low QG models

GeV

Dvali & Gabadadze (1999)

( ) Scales of n n B L V in theory 

  • 3

2    

WK L B

 

10

00 10 0110 02 10 0310 04 10 05 10 0610 07 10 08 10 09 10 1010 1110 12 10 13 10 14 10 1510 1610 17 10 18 10 19 10 20

nn nn 5  

L B

GeV

L B

Supersymmetric Seesaw for m BL , LR

Mohapatra & Marshak (1980) Dutta-Mimura-Mohapatra (2005)

Non-SUSY model

Left-Right symmetric GUT

SUSY GUT PDK Plank scale 4

Experimental motivation! large increase of sensitivity: factor of 1,000 is possible compared to existing limit

Post‐Sphaleron Baryogenesis Babu, Mohapatra, et al.(2013)

Goity, Sher (1994) Berezhiani Bento (2005)

Observable effects at LHC Berezhiani; Babu et al. (2013)

Shrock & Nussinov (2002)

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For experimental "quasifree conditions" when external fields are approx. and "observation" time ~ 0.1 s to 1 0 s n t

2

n

n nn

t P t

æ ö ÷ ç ÷ = ç ÷ ç ÷ ç è ø

2

for fre sens e ne itivi utrons ty N t P ⋅  

2 nn free

N t t t = ⋅ 

24

is characteristic "oscillation" time [ , as presently known] Existing exp. limits are set by at ILL (free ) and by Super-K (bound 10 ) 2

nn

e n n V a t a

  • =

< ⋅ 

25 26

  • bservable

Predictions of t effect around heoret ~ 1 ical models: 10 eV a

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HFR @ ILL 57 MW Cold n-source 25 D2

fast n, background Bended n-guide Ni coated, L ~ 63m, 6 x 12 cm

2 58

H53 n-beam ~1.7 10 n/s .

11

(not to scale) Magnetically shielded 95 m vacuum tube Annihilation target 1.1m E~1.8 GeV Detector: Tracking& Calorimetry Focusing reflector 33.6 m

Schematic layout of Heidelberg - ILL - Padova - Pavia nn search experiment at Grenoble 89-91

Beam dump ~1.25 10 n/s

11

Flight path 76 m < TOF> ~ 0.109 s

Discovery potential : N t

n 

 

2 9

15 10 . sec Measured limit : nn   8 6 107 . sec

At ILL/Grenoble reactor in 89‐91 by Heidelberg‐ILL‐Padova‐Pavia Collaboration

  • M. Baldo-Ceolin et al., Z. Phys., C63 (1994) 409

Previous state‐of‐the‐art n‐nbar search experiment with free neutrons

18 2 9 2

8 No candidates observed. Limit set for a year of running: with L ~ 76 m and 0.109 sec measured 1.606 10 sensitivity: No GeV back 1.5 10 grou s d s n !

"ILL sensitivity unit"

0.86 10

nn

nn t P N t

s t

  • =

< ´ ⋅ = ´

> ´

 ~ 700 m/s

n

v

6

Top view of horizontal experiment

n n

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Free Neutron and Bound Neutrons NNbar Search Limits Comparison

Large improvement with free‐neutron experiments is possible

2 bound free

R t t = ´

intranuclear search exp. limits: Super-K, Soudan-2 Frejus, SNO

Free neutron search limit (ILL - 1994)

Ultimate goal of new n-nbar search with free neutrons

Factor of 1,000 sensitivity increase

7

Recent S‐K (2011) limit based

  • n 24 candidates

and 24.1 bkgr.

Post‐Sphaleron Baryogenesis Babu et al

was discussed by Ed Kearns R

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  • N. Mokhov, MARS simulations, FNAL, 2011

~ 1.3 GeV

Yield is ~ 24 neutrons per GeV proton ~ 1.5 1017 n/s/MW

For target made of fissionable materials (e.g. Th, DU) neutron yield can be factor ~ 2 higher (geometry dependent)

Spectrum of primary fast n from spallation target and from fission (Courtesy of Gary Russel).

Potential source of the “fast ” background for n‐nbar that was non‐existent in the previous ILL experiment

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Spallation Target in Project X

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The Institut Laue Langevin 58 MW High Flux Reactor is

  • ptimized to serve many neutron beamlines

Geoff Greene/UT 10

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Core Vessel water cooled shielding Core Vessel Multi-channel flange Outer Reflector Plug Target Inflatable seal

Tony Gabriel/UT/SNS

Spallation 1MW target at SNS

p

11

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Configuration (A) G. Muhrer/LANL

A

D2O LD2 Pb Initial UT model (C) L. Castellanos/UT

C

Configuration (B)

  • F. Gallmeier/SNS

with LH2

B A B C

Preliminary Energy spectrum of neutron currents in different models

Pb D2O LD2

1 MW P 1 GeV

~ 1m2 @ 1m 12

H2O Fe

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D ~ 4 m

Conceptual Horizontal Baseline Configuration

with elliptical focusing reflector (method proposed by us in 1995)

Typical initial baseline parameters: Cold source configuration C Luminous source area, dia 30 cm Annihilation target, dia 200 cm Reflector starts at 2 m Reflector ends at 50 m Reflector semi‐minor axis 2.4 m Distance to target 200 m Super‐mirror m=7 Vacuum < 105 Pa Residual magnetic field < 1 nT MC Simulated sensitivity Nt2: 150 “ILL units” x years Sensitivity and parameters are subject of optimization by Monte‐ Carlo including overall cost

13

N‐nbar effect can be suppressed by weak magnetic field.

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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

  • r free = 1.8 109 s

Sensitivity Nt2 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.

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Fermilab PAC recommendation sets for horizontal option a “minimal sensitivity goal” of ~ 30 or free = 5108 s

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Free Neutron and Bound Neutrons NNbar Search Limits Comparison

Large improvement with free‐neutron experiments is possible

2 bound free

R t t = ´

Factor of 1,000 sensitivity increase

16

Recent S‐K (2011) limit based

  • n 24 candidates

and 24.1 bkgr.

Post‐Sphaleron Baryogenesis Babu et al

PX horizontal PX vertical

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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 tfree ~ 1.8´109 sec New technologies (R&D and cost‐impact studies are required)

  • 1. Use vertical layout of experiment with flight path ~ 200 m
  • 2. Use “4p 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 tfree up to 1´1010 sec.

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SLIDE 18

Exam ple of Vertical layout

Vacuum Tube and

  • Mag. Shield

L ~ 100 m Dia ~ 5 m Focusing Super-m Reflector L ~ 20m L~100 m dia ~ 4 m

2 2 2 2 2 2

2 1 2 Vertica 105 l layout enab 100 les use of the whole cold spectrum incl.UCN = s m 105 m 4.9 m/s s m/s 10 m/s = s+4.9 m/s s 1 1 3.7 3.7

h v t gt

⋅ + ⋅ ⋅ ⋅

= +

18

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``` Heavy Metal Target: Pb, Bi, W, Ta Heavy Water Liquid Deuterium Solid D2 UCN Converter High-m Super Mirror

  • r diamond

nanoparticles reflector Graphite Reflector

Further sensitivity improvement concept: dedicated spallation target with VCN-UCN converter (4 emission)

(view along the beam) Scheme being optimized by simulations

19

Cold Neutrons R&D on reflector configuration ,

  • ptimization ,
  • rad. stability,

and cost

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20

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Fit to the Spectrum 13 MeV, CH4, 6K

Dave Baxter, Chen‐Yu Liu / Indiana U.

Colder moderator R&D at Indiana University / CEEM

Cold moderator

  • tech. development

Super‐m acceptance

  • tech. development

21

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Comparison with other Sources for N‐Nbar Search

  • Research reactors (HFIR/ORNL 85 MW; ILL/France 58 MW; NIST 20 MW, etc.) are

generally not available for HEP experiments. If would be available the advantage

  • f high flux will be depreciated by inability of allowed source modifications (NRC etc.)

Possible sensitivity ~ 300 “ILL units” ´ years.

  • Spallation sources: SNS 1 MW, ESS 5 MW are multi‐user facility with small fraction
  • f total flux, real estate, and time. Spallation process produce factor of ~ 5 more

neutrons per MW. Possible sensitivity ~ 50 “ILL units” ´ years.

  • Dedicated facility like Spallation Target in Project X ~ 1 MW allows optimization of

the source configuration, large acceptance due to close location of experiment, 4p cold neutron concentration, vertical layout of experiment. These features are unique for cold neutron sources and might be advantageous for other future cold and ultra‐cold neutron experiments. E.g. n‐EDM search can benefit from high cold neutron flux optimized for N‐Nbar search. Possible horizontal baseline NNbarX sensitivity ~ 450 “ILL units”

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Progress in neutron super-mirrors

v  50 m/s

Commercial products of Swiss Neutronics v 30 m/s

(H. Shimizu, 2012)

Super‐mirrors material for large elliptical focusing reflector

24

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Annihilation feature: 5 n C p + 

25

  • Use concepts of backgroundless ILL detector;
  • Can be Horizontal or Vertical;
  • Carbon‐film annihilation target;
  • Tracker for vertex to thin carbon target;
  • Calorimeter for trigger and energy reconstruction;
  • TOF before and after tracker to remove

vertices of particles coming from outside;

  • Cosmic veto;
  • Intelligent shielding and beam dump

to minimize (n,) emission.

  • R&D on detector configuration and cost
  • ptimization by NCSU, IU, and India

together with FNAL