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Nab experiment: progress update Dinko Po cani c, for the Nab Collaboration University of Virginia FnPB PRAC Review 15 December 2010 D. Po cani c (UVa) Nab progress update 15 Dec 10 1 / 27 n-decay program at FnPB The FnPB

slide-1
SLIDE 1

Nab experiment: progress update

Dinko Poˇ cani´ c, for the Nab Collaboration

University of Virginia

FnPB PRAC Review 15 December 2010

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 1 / 27

slide-2
SLIDE 2

n-decay program at FnPB

The FnPB neutron decay program at SNS

◮ Nab: a precise measurement of

  • a, the electron-neutrino correlation in neutron decay, and
  • b, the Fierz interference term, never before measured in n decay.

◮ Polarized program (abBA/PANDA): precise measurements of

  • A, the electron asymmetry in neutron decay,
  • B, the neutrino asymmetry in neutron decay,
  • C, the proton asymmetry in neutron decay; also
  • independent measurements of a and b.

Typical goal uncertainties: δv/v ≤ 10−3, and δb ≤ 3 × 10−3.

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 2 / 27

slide-3
SLIDE 3

Motivation, goals

Neutron Decay Parameters (SM)

dw dEedΩedΩν ≃ keEe(E0 − Ee)2 ×

  • 1 + a
  • ke ·

kν EeEν + b m Ee + σn ·

  • A
  • ke

Ee + B

  • kν

Eν

  • + . . .
  • where:

a = 1 − |λ|2 1 + 3|λ|2 A = −2|λ|2 + Re(λ) 1 + 3|λ|2 B = 2|λ|2 − Re(λ) 1 + 3|λ|2 λ = GA GV (with τn ⇒ CKM Vud) also: C = κ(A + B) where κ ≃ 0.275 .

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 3 / 27

slide-4
SLIDE 4

Motivation, goals

Goals of the Nab experiment

◮ Measure the electron-neutrino parameter a in neutron decay

with accuracy of ∆a a ≃ 10−3 current results: −0.1054 ± 0.0055 Byrne et al ’02 −0.1017 ± 0.0051 Stratowa et al ’78 −0.091 ± 0.039 Grigorev et al ’68

◮ Measure the Fierz interference term b in neutron decay

with accuracy of ∆b ≃ 3 × 10−3 current results: none

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 4 / 27

slide-5
SLIDE 5

CKM matrix: Vud

Status of A and λ in n decay

  • 0.13
  • 0.12

Beta Asymmetry A

  • 0.11
  • 0.10

Abele-09 Pattie-09 Abele-02 Liaud-97 Yeroz-97 Bopp-86 Average: =-0.1186(9) A

Uncertainty of the average scaled up by factor 2.3× Global fit χ2/dof = 28/5 ! Statistical probability for this χ2 is 5 × 10−5.

  • H. Abele, private communication (2009).

R.W. Pattie, et al., PRL 102, 012301 (2009).

  • H. Abele et al., PRL 88, 211801 (2002).
  • P. Liaud et al., NP A 612, 53 (1997).
  • B. Yerozolimsky et al., PL B 412, 240 (1997).
  • P. Bopp et al., PRL 56, 919 (1986).
  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 5 / 27

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SLIDE 6

CKM matrix: Vud

Status of A and λ in n decay (cont’d)

Nab goal value of ∆a: ⇒ ∆λ ≃ 3.5 × 10−4 i.e., an order of magn. improvement.

∆λ λ ≃ 0.27 ∆a a ≃ 0.24 ∆A A

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 6 / 27

slide-7
SLIDE 7

Beyond Vud

n-decay Correlation Parameters Beyond Vud

◮ Beta decay parameters constrain L-R symmetric, SUSY extensions to

the SM. [Reviews: Herczeg, Prog. Part. Nucl. Phys. 46, 413 (2001),

  • N. Severijns, M. Beck, O. Naviliat-ˇ

Cunˇ ci´ c, Rev. Mod. Phys. 78, 991 (2006), Ramsey-Musolf, Su, Phys. Rep. 456, 1 (2008)]

◮ Fierz int. term, never measured for the n, along with B, offers a

sensitive test of non-(V − A) terms in the weak Lagrangian (S, T). [S. Profumo, M. J. Ramsey-Musolf, S. Tulin, PRD 75, 075017 (2007)]

◮ Measurement of the electron-energy dependence of a and A can

separately confirm CVC and absence of SCC. [Gardner, Zhang, PRL 86, 5666 (2001), Gardner, hep-ph/0312124]

◮ A connection exists between non-SM (e.g., S, T) terms in d → ue¯

ν and limits on ν masses. [Ito + Pr´

ezaeu, PRL 94 (2005)]

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 7 / 27

slide-8
SLIDE 8

Beyond Vud non-V − A interaction terms

Updated limits for RH S and T currents n decay

  • 0.15
  • 0.10
  • 0.05

0.00 0.05 0.10 0.15

  • 0.15
  • 0.10
  • 0.05

0.00 0.05 0.10 0.15

RS/LV

RT/LA

neutronandnucleardecays (survey,95%C.L.) “presentlimits” (68%C.L.) Δχ

2

C.L. 2.30 68.3% 90% 95.4% 4.61 6.17 neutrino mass (68%C.L.) neutrinomass (68%C.L.) muondecay “90%C.L.”

Present limits (n decay data) (SM values at origin of plot.)

S V

  • 0.15
  • 0.10
  • 0.05

0.00 0.05 0.10 0.15

  • 0.15
  • 0.10
  • 0.,05

0.00 0.,05 0.10 0.15

R /L

RT/LA

neutron and nucleardecays (survey,95%C.L.) Δχ

2

C.L. 2.30 68.3% 90% 95.4% 4.61 6.17 neutrinomass (68%C.L.) neutrinomass (68%C.L.) “futurelimits” (68%C.L.) muondecay “90%C.L.”

Projected limits; Grey contours: β compilation [Sev-06]

Improvement from more precise a = −0.1030(1); using b ≡ 0.

[G. Konrad, W. Heil, S. Baeßler, D. Poˇ cani´ c, F. Gl¨ uck, arXiv 1007.3027.]

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 8 / 27

slide-9
SLIDE 9

Beyond Vud non-V − A interaction terms

Limits for LH S and T currents n decay

LS/LV

  • 0.3
  • 0.2
  • 0.1

0.0 0.1 0.2 0.3

  • 0.3
  • 0.2
  • 0.1

0.0 0.1 0.2 0.3

LT/LA

Δχ

2

C.L. 2.30 68.3% 90% 95.4% 4.61 6.17 neutronand nucleardecays (survey,68%C.L.) superallowed 0 →0 decays (68%C.L.)

+ +

“presentlimits” (68%C.L.) muondecay “90%C.L.” nucleardecays ( (In),90%C.L.) P

107

Present limits (n decay data) (SM values at origin of plot.)

  • 0.04
  • 0.02

0.00 0.02 0.04

  • 0.04
  • 0.02

0.00 0.02 0.04

LS/LV

LT/LA

Δχ

2

C.L. 2.30 68.3% 90% 95.4% 4.61 6.17 “futurelimits” (68%C.L.) superallowed 0 →0 decays (68%C.L.)

++

neutronand nucleardecays (survey,68%C.L.) nucleardecays ( (In),90%C.L.) P

107

0.04

Projected limits assuming a = −0.1030(1) ; b = 0 ± 0.003 [G. Konrad, W. Heil, S. Baeßler, D. Poˇ cani´ c, F. Gl¨ uck, arXiv 1007.3027.]

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 9 / 27

slide-10
SLIDE 10

Beyond Vud non-V − A interaction terms

Right-handed W bosons

Adding RH gives non-zero δ = m2

1/m2 2, ζ:

W1 = WL cos ζ + WR sin ζ , and W2 = −WL sin ζ + WR cos ζ .

Mixingangle ζ

  • 0.2
  • 0.1

0.0 0.1 0.00 0.02 0.04 0.06 0.08 0.10

Massratio δ

250 Δχ

2

C.L. 2.30 68.3% 90% 95.4% 4.61 6.17 300 350 400 450 500 550 600

Massm[GeV]

2

lepton scattering (90%C.L.) μ decays (68%C.L.) μ decays (90%C.L.) DØ(95%C.L.) 0 →0 decays (68%C.L.)

+ +

“present limits” (68%C.L.)

Present limits

Δχ

2

C.L. 2.30 68.3% 90% 95.4% 4.61 6.17

Mixingangle ζ

Massratio δ

400 500 600 900 700 800 1000

Massm[GeV]

2

  • 0.10
  • 0.05

0.00 0.05 0.00 0.01 0.02 0.03 0.04 0.05

Δχ

2

C.L. 2.30 68.3% 90% 95.4% 4.61 6.17 0 →0 decays (68%C.L.)

+ +

μ decays (90%C.L.) DØ(95%C.L.) μ decays (68%C.L.) lepton scattering (90%C.L.) “futurelimit” (68%C.L.)

Projected limits [G. Konrad, W. Heil, S. Baeßler, D. Poˇ cani´ c, F. Gl¨ uck, arXiv 1007.3027.]

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 10 / 27

slide-11
SLIDE 11

Beyond Vud Fierz interference term

The Fierz interference term b

b can be estimated from nuclear beta decays: bF = CSCV |CS|2 + |CV |2 bGT = CTCA |CT|2 + |CA|2 These terms vanish for pure ν(R) coupling. b = 0 only for S, T coupling to ν(L). (leptoquarks?) From 0+ → 0+ decays [Towner + Hardy ’98]: |bF| ≃ |CS| |CV | ≤ 0.0077 (90 % c.l.) From analysis of GT decays [Deutsch + Quin, ’95]: bGT = −0.0056(51) ≃ CT |CA| (small FT from πe2γ!?) ⇒ a ∼ 10−3 measurement of bn is very interesting!

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 11 / 27

slide-12
SLIDE 12

Beyond Vud Second class currents

Correlation Parameters with Recoil Correction

[Gardner, Zhang, PRL 86, 5666 (2001), Gardner, hep-ph/0312124]

Most general form of hardonic weak current consistent with (V-A): p(pp)|Jµ|n(pn, P) = ¯ up(pp)

  • f1(q2)γµ − if2(q2)

Mn qµ + f3(q2) Mn qµ + g1(q2)γµγ5 − ig2(q2) Mn σµνγ5qν + g3(q2) Mn γ5qµ

  • un(pn, P)

a, A, B ⇒ λ = g1 f1 while τn ∝ (f1)2 + 3(g1)2 However, f2 (weak magnetism) and SCC’s (g2, g3), remain unresolved in beta decays (best tested in A=12 system). With recoil corrections, Gardner and Zhang find: a(Ee) = func(f2) while A(Ee) = func(f2, g2)

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 12 / 27

slide-13
SLIDE 13

Beyond Vud Second class currents

0.4 0.5 0.6 0.7 0.8 0.9 x

  • 0.008
  • 0.006
  • 0.004
  • 0.002

0.002 0.004 a

(1) and A (1)

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 13 / 27

slide-14
SLIDE 14

Comparison w/other experiments

Current experiments aiming to measure a

  • 1. Nab: goal is to measure ∆a/a ∼ 10−3

◮ Best statistical sensitivity, ◮ Challenging but manageable systematics, esp. in asymm. design.

  • 2. abBA: goal is to measure ∆a/a ∼ 10−3

◮ Similar to Nab, but with spectrometer configured for A,B/C, ◮ Detection function is very broad, syst. uncert. for a very demanding.

  • 3. aCORN: goal is to measure ∆a/a ∼ 0.5 − 2 %

◮ Funded, under construction, ◮ Uses only part of neutron decays.

  • 4. aSPECT: aims to measure ∆a/a ∼ 10−3

◮ Funded and running; recently overcame trapping problems, ◮ Stat. sensitivity not as good as Nab due to integration; presently

∼ 2 %/day—will likely improve on publ. results, not < 1 % this yr,

◮ Easier determination of detection function than in Nab at the present

level of accuracy. Singles measurement!

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 14 / 27

slide-15
SLIDE 15

Nab measurement principles

Nab Measurement principles: Proton phase space

Ee (MeV) pp2 (MeV2/c2) cos θeν = -1 cos θeν = 1 cos θeν = 0 proton phase space probability (arb. units) Ee = 75 keV 236 keV 450 keV 700 keV

0.5 1 1.5 0.2 0.4 0.6 0.8

NB: For a given Ee, cos θeν is a function of p2

p only.

Slope = a

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 15 / 27

slide-16
SLIDE 16

Nab measurement principles

Nab principle of operation

◮ Collect and detect

both electron and proton from neutron beta decay (magnetic field, detectors at both ends)

◮ Measure electron

energy and proton TOF and reconstruct decay kinematics (Magnetic field shape, silicon detectors at both ends). Segmented Sidetector Segmented Sidetector TOFregion (field ∙ ) r B

B

Uup (upperHV) Udown (lowerHV) magneticfilter region(field ) B0 decayvolume (field ∙ ) r B

B,DV

Neutron beam

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 16 / 27

slide-17
SLIDE 17

Nab apparatus and installation

Nab spectrometer: magnetic field profile

466.25 0.03 5.00 25.28 43.81 37.50 0.50 481.25 14.75 25.90 67.09 0.47 41.66 14.77 25.90 4.34 4.34 10.52 20.58 38.16 3.13 3.13 29.94 16.41 30.24 3.19 3.28 4.93 12.92 8.00 16.77 c1i z r c6i c4i c5i c3i c2i c1o c6o c4o c5o c3o c2o Magneticfield [T] B z [m] z [cm] 1 20

  • 1

2

  • 20

3 10 4

  • 10

5

  • 30

1 2 3 4 5 Bz (on axis) Bz (on axis) Bz (off axis)

Magneticfield [T] B

1 2 3 4 5 Decay volume Decay volume Si detector Filter 4 mflightpath isomitted here

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 17 / 27

slide-18
SLIDE 18

Nab apparatus and installation

Si detector prototypes (15 cm diameter)

LANL group has full-size prototypes from Micron Corp. Full thickness t = 2 mm; dead layer thickness td ≤ 100 nm. Detailed testing currently under way at LANL.

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 18 / 27

slide-19
SLIDE 19

Nab apparatus and installation

Spectrometer installation:

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 19 / 27

slide-20
SLIDE 20

Nab apparatus and installation

Nab anti-magnetic shield (AMS)

X Y 30 20 100 10 5 30 50 20 100 Anti-magnetic solenoids Inner solenoids

Top view: Side view:

Spectrometer magnet

Staging area for Nab would save FnPB beam time during AMS testing.

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 20 / 27

slide-21
SLIDE 21

Nab apparatus and installation

Nab: DAQ

Detector& preamps

PIXIE- 16

R5400n controller PNChp 30kV

rearI/O module

FS725 Rbfreq

PIXIE- 16

PXI crate

PXI-PCI 8336 … x8 … x16 … x16

DAQ workstation Analysis workstation RAID storage Detector& preamps

PIXIE- 16

R5400n controller PNChp 30kV

rearI/O module PIXIE- 16

PXI crate

PXI-PCI 8336 … x8 … x16 … x16

  • ptical

signal Isolation transformer power 120 V Isolation transformer

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 21 / 27

slide-22
SLIDE 22

Schedule, milestones

Milestone Completion 0.a Start of project Jul 2011 0.b Detector prototype detects protons

  • Sep. 2011

0. Magnet design ready for bidding

  • Sep. 2011

1.a Order for magnet placed (design & option to build)

  • Dec. 2011

1.b Acceptance of engineering drawings

  • Dec. 2012

1.c Delivery of magnet

  • Sep. 2013

1. Spectrometer magnet accepted

  • Dec. 2013

2.a Passive Anti-Magnetic screen: magnetic design finished

  • Sep. 2012

2. Passive Anti-Magnetic screen built

  • Dec. 2013

3.a Detector test chamber available

  • Mar. 2012

[ . . . ] 3.g Electrode system ready

  • Mar. 2014

3. Main detectors work in spectrometer

  • Jun. 2014

4.a Shielding calculation for Nab accepted

  • Jun. 2013

[ . . . ] 4.d Shielding and utilities ready

  • Jun. 2014

4. Spectrometer ready for data taking

  • Sep. 2014

5.a Magnetometer calibrated

  • Sep. 2012

5.b Magnetic field mapping system constructed

  • Dec. 2013

5. Magnetic field of spectrometer mapped

  • Mar. 2014

6. Data acquisition

  • Sep. 2015

7. Data analysis

  • Sep. 2016
  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 22 / 27

slide-23
SLIDE 23

Nab collaborators

  • R. Alarcon1, L.P. Alonzi2§, S. Baeßler2∗, S. Balascuta1§, J.D. Bowman3†,

M.A. Bychkov2, J. Byrne4, J.R. Calarco5, V. Cianciolo3, C. Crawford6,

  • E. Frleˇ

z2, M.T. Gericke7, F. Gl¨ uck8, G.L. Greene9, R.K. Grzywacz9,

  • V. Gudkov10, F.W. Hersman5, A. Klein11, M. Lehman2§, J. Martin12,
  • S. McGovern2§, S.A. Page6, A. Palladino2§, S.I. Penttil¨

a3‡, D. Poˇ cani´ c2†,

  • R. Rodgers2§, K.P. Rykaczewski3, W.S. Wilburn11, A.R. Young13.

1Arizona State University 2University of Virginia 3Oak Ridge National Lab 4University of Sussex

  • 5Univ. of New Hampshire

6University of Kentucky 7University of Manitoba

  • 8Uni. Karlsruhe/RMKI Budapest

9University of Tennessee 10University of South Carolina 11Los Alamos National Lab 12University of Winnipeg 13North Carlolina State Univ. †Co-spokesmen ∗Experiment Manager ‡On-site Manager §Graduate Students

Home page: http://nab.phys.virginia.edu/

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 23 / 27

slide-24
SLIDE 24

Additional slides Detector response

Additional slides

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 24 / 27

slide-25
SLIDE 25

Additional slides Detector response

Electron energy response

histoE_N

Entries 85243 Mean 1.263 RMS 0.658

Number of bounces 1 2 3 4 5 6 7 8 Yield 10

2

10

3

10

4

10

5

10 histoE_N

Entries 85243 Mean 1.263 RMS 0.658 Number of bounces

above threshold

(10 keV upper det.) (40 keV lower det.)

all bounces

histoEe300idealsum

Entries 85243 Mean 298.9 RMS 9.131 detected Ee [keV] 100 200 300 400 500 600 700 800 Yield 1 10

2

10

3

10

4

10

5

10

histoEe300idealsum

Entries 85243 Mean 298.9 RMS 9.131 Ee in both detectors

histoEe300esc Entries 85243 Mean 1.203 RMS 12.1 non-detected Ee [keV] 50 100 150 200 250 300 Yield 1 10

2

10

3

10

4

10

5

10 histoEe300esc Entries 85243 Mean 1.203 RMS 12.1 Ee loss in escaped particles

in dead layer escaped particle

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 25 / 27

slide-26
SLIDE 26

Additional slides Detector response

Detector response: Electron energy Proton TOF

10 100 1000 10000 100000 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02 1/TOF^2 [us^-2] Yield

Ee = 75 keV Ee = 75 keV, Ee response Ee = 225 keV Ee = 225 keV, Ee response Ee = 375 keV Ee = 375 keV, Ee response Ee = 525 keV Ee = 525 keV, Ee response Ee = 675 keV Ee = 675 keV, Ee response

1/TOF2 spectra for protons. The solid lines show the 1/TOF2 spectra for perfect electron detection. The

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 26 / 27

slide-27
SLIDE 27

Additional slides Detector response histoETOF300du

Entries 5134 Mean 33 RMS 6.017

TOF [ns]

  • 200
  • 150
  • 100
  • 50

50 100 150 200 Yield 1 10

2

10

3

10

histoETOF300du

Entries 5134 Mean 33 RMS 6.017

Camel hump curve

lower det hit first upper det hit first

TOF = time of upper det. hit − time of lower det. hit

  • D. Poˇ

cani´ c (UVa) Nab progress update 15 Dec ’10 27 / 27