nab ill 2011nab.phys.virginia.edu/slides/nab_ill_2011.pdf · 2011-07-14 · neutron lifetime...
TRANSCRIPT
The planned Nab/abBA/PANDA spectrometer
Stefan Baeβler
The Spallation Neutron Source SNS in Oak Ridge, TN
Linear H- accelerator Accumulator ring (buncher)
Target
TargetGuide Hall
Usage of neutrons @ SNS
11A - Powder Diffractometer Commission 2007
7 - Engineering Diffractometer IDT CFI Funded C i i 2008
9 –VISION
12 - Single Crystal Diffractometer Commission 2009
Commission 2008
6 - SANS Commission 2007
4B - Liquids
5 - Cold Neutron Chopper Spectrometer Commission 2007
13 - Fundamental Physics Beamline Commission 2008
4A - Magnetism Reflectometer C i i 2006
ReflectometerCommission 2006
14B - Hybrid Spectrometer Commission 2011
3 - High Pressure Diffractometer Commission 2008
Commission 2006
18 - Wide Angle
17 - High Resolution Chopper Spectrometer
15 – Spin Echo
1B - Disordered Mat’lsCommission 2010
2 - Backscattering Spectrometer Commission 2006
18 Wide Angle Chopper Spectrometer Commission 2007
Commission 2008
Performance of FNPB beamline
Wrap-around neutrons
Measured (@1 MW) neutron capture flux at FNPB beam exit: 9c 2
14 10 @ 1.4 MWcm s
F = ´ ⋅
Neutron beta decay
p+e-
n
n
e
Beta Decay in the Standard Model
60Co
I
I
e-
≠
Fermi’s golden rule:2
weak2 decay probability i f f H i
Parity Violation found by Wu et al, 1956
5G Ve-
60Co
ud 5Fweak 5 h.c.
21 μ μ e
GH p γ γ γ n e γ γ γ νV
3 Helicity1 Quark mixing 2 Nucleon structure 3. Helicity
… of elementary fermions: –p/E,
μ- νμ
1. Quark mixing
2 95%V
2. Nucleon structure effects
gV = GF·Vud·1
… of elementary anti-fermions: +p/E
e
d u
s c
2ud 95%V
gA = GF·Vud·λ
No nuclear structure effectse-
e
epb t
c
(for neutrons)
Observables in Neutron Beta Decay
pe-
n e
Jackson et al., PR 106, 517 (1957):
Observables in Neutron beta decay, as a function of generally possible coupling constants (assuming only
22 22 1 3Vdw G E
pn
e
generally possible coupling constants (assuming only Lorentz-Invariance)
2 ee1 3 1 b md E p p
d eue
1 3F VG EdE
2 ee
e
e e
ee
1 3 1
+
a b
A B
dw EE
p pE E
p p p pD
Fierz interference term 0b
e en
e e
+ A Bp p p pE E E E
D
2 R Beta-Asymmetry
Neutrino-Electron-Correlation
2
Re2
1 3A
2
2
1a
u1 2 2
e2
n d2 1 3FG V E
Neutron lifetime
21 3
The Standard Model Parameters Vud and λ
νe
2
1pFermi-Decay:
gV = GF·Vudνee- e- A = 0S = 0, mS = 0
n
Gamow-Teller-Decay:p
2
1 νe νee- e- A = 0S = 1, mS = 0y
gA = GF·Vud·λ
p e- νe A = -1S = 1, mS = 1
n1 cos ,ee
e
pdw A pE
, S
(after D. Dubbers, Prog. Part. Nucl. Phys. 26, 173 (1991)
Two unknown parameters, gA and gV, need to be determined in 2 experiments
1. Neutron-Lifetime: 1 2 2n V A3g g n 885 s
2
22 0.11 3
A
A
V
gg
2. Beta-Asymmetry:
Neutron Lifetime Measurements
Decrease of Neutron Counts N with storage time t: N(t) = N(0)exp{-t/τeff}
1/ τeff = 1/τβ+1/τwall losses895
Spivak 88
Nesvizh.92
Byrne 96
Arzumanov Nico 05
PDG2010
890
me
[s]
Mampe 89 00 PDG2010
Pichlmaier 10
Serebrov 08885
Neu
tron
life
tim
Mampe 93Serebrov 05
Serebrov 10875
880
Many new attempts mostly with UCN in magnetic bottles: Ezhov et al (ILL PNPI Gatchina)
1988 1992 1996 2000 2004 2008 2012Experiment publication
Many new attempts, mostly with UCN in magnetic bottles: Ezhov et al. (ILL, PNPI Gatchina), Arzumanov et al. (Kurchatov Inst., ILL), Liu et al. (Indiana), Paul et al. (TUM), Huffman et al. (NIST, NCSU), Nico et al. (NIST), Zimmer et al., (ILL) are (at least) under construction.
The Beta Asymmetry
p+
n
e-
-1.255
e
Electron Detector (Plastic Scintillator)
Yerozolimski
Liaud
PDG20101 265
-1.26
( )
Decay Electrons
PERKEO I
Mostovoi
PDG2010
-1.27
-1.265
λPolarized Neutrons
Decay ElectronsPERKEO II
UCNA
PERKEO II,prelim-1.28
-1.275
1985 1990 1995 2000 2005 2010Publication year
Ongoing funded experiments:Split Pair Magnet
Magnetic Field PERKEO II
Ongoing funded experiments:UCNA (NCSU, LANL), PERKEO III (Heidelberg), PERC (Europe)
Use of coupling constants in Primordial Nucleosynthesis
W±
e-p
W±
νepBefore Phase Transition:
Equilibrium W±
e-p
νen
n + νe ↔ p + e-
e+n
n + e+ ↔ p + νe
After Phase Transition (some minutes
n ↔ p + e-+ νe
νen
After Phase Transition (some minutes after Big Bang):
n + p→ d + γ d + d→ 3He + n → t + p
d + 3He→ 4He + pd + He→ He + p
Then the Primordial Nucleosynthesis stops, as there are no stable nuclei with A = 5, 8, and as h f di
…..
the free neutrons die out.
Stronger coupling constants in n ↔ p reactions⇒ Phase transition later⇒ nucleon density lower after phase transition⇒ less 4He, more d
Search for Standard Model Parameters
0.980
0.975ft(0+→0+) [Hardy09]ft(0+→0+) [Liang09 – DD-ME2]
Kaons+Unitarity [PDG 2010]
0.970V ud
ft(0+→0+) [Liang09 – PKO1] PIBETA [Pocanic04]
0.965 PDG
201
0]
010]
0 960λ
[P
A[U
CN
A 2
0
-1.290 -1.280 -1.270 -1.260λ = gA/gV
0.960
A [PERKEO II, prel.]
Unitarity and superallowed nuclear decaysV Telegdi 1977:V. Telegdi, 1977:I would like to say that the theory of β-decay is the theory of the decay of the neutron. I have always thought that nuclear β-decay experiments were only done faute de mieux: … If you do not know how to do the one experiment, you take the average of twenty.
( )
22 2V F ud
2ud 2
12 1 V
Ft g G V
VG Ft
µ =
µ+D( )F2 1 RG Ft+D
2 2 21 VV Vuud s ub1 VV V= - -(Dubbersaverage)
Liang et al., PRC 79, 064316 (2009)Dubbers, Schmidt, RMP (2011), in press
Possible Tests of the Standard Model
1 S h f Ri ht h d d C t (l t i hth d d) W ?
Multiple determinations (nuclear physics, other correlation coefficients) overconstrain problem, enable:
1. Search for Right-handed Currents (leptons are righthanded): WR?
2. Search for Scalar and Tensor interactions (neutrinos have opposite handedness to electrons – 4 new coupling constants possible):
Leptoquarks? Charged Higgs Bosons? Supersymmetry?
3. Test of the Unitarity of the Cabbibo-Kobayashi-Maskawa-Matrix:
ud u ubsd ' dVV V
Extra Z bosons? Supersymmetry? 4th quark generation?
2 95%Vcd cs cb
td td tb
s ' sb ' b
V V VV V V
d u
s c
2ud 95%V
2us 5%V
us2 2
ubu2
d 1 ?V VV+ + = +b t
c2
ub 0.000015V
Determination of the Coupling Constants
νe
2
1pFermi-Decay:
gV = GF·Vudνee- e- a = 1
n
Gamow-Teller-Decay:p
2
1 νe νee- e- a = 1y
gA = GF·Vud·λ
p e- νe a = -1
1 cos ,ee
vdw a p pc
Two unknown parameters, gA and gV, need to be determined in 2 experiments
1. Neutron-Lifetime: 1 2 2n V A3g g n 885 s
A
V
gg
2b. Neutrino-Electron-Correlation a:2
2
1 ~ 0.11 3
a
e-
Idea of the cos θeν spectrometer Nab @ SNS
p n
e
epKinematics:
• Energy Conservation:
• Momentum Conservatione,max eEE E
Proton phase space (Dalitz plot) Probability (arb. units)1 5
1 cosee
e
pdw aE
e• Momentum Conservation
2 2 2e ep 2 cos ep p p p p
cos θeν = 1
Proton phase space (Dalitz plot) Probability (arb. units)
1
1.25
1.5Ee =
236 keV700 keV
[MeV
2 /c2 ]
0.75
1
75 keV 22p emin, max
Edges:
Slope:
p p p
p p2
[
0.25
0.5 cos θeν = 0cos θeν = -1 450 keV
2ep
e
Slope:
1 cos epa pE
Ee [MeV]
00 0.2 0.4 0.6 0.8Alternative approaches: aSPECT (Mainz, ILL), aCORN (Tulane, NIST)
The asymmetric version of Nab @ SNS
30 kV
Advantages of asymmetric configuration:
D i f i I d fli h h
SegmentedSi detector
TOF region• Detection function: Improved flight path length
• Reduced sensitivity to electrostatic and ti t ti l i h iti
magnetic filterregion (field B0)
g(field rB·B0)
magnetic potential inhomogeneities
• Avoid deep Penning trap
• Statistical uncertainty: Bigger decay
decay volume (field rB,DV·B0)
0 kV y gg yvolume vs. angular acceptance
• Polarized experiment (abBA, PANDA) still possible
0 kV
0 kV
Neutronbeam
0 kV
The cosθeν spectrometer Nab @ SNSut
ion
2ep
e
1 cos epa pE
SegmentedSi detector
-30 kV
p p2di
strib
u
2pcos 1e p
2pcos 1e p
magnetic filteri (fi ld B )
TOF region(field rB·B0)
107
pp2 [MeV2/c2]
0.0 0.5 1.0 1.5
Ee = 550 keVregion (field B0)
decay volume (field rB,DV·B0)
nt ra
te 106
107
Neutronbeam
0 kV
Sim
ulat
ed c
oun
Ee = 300 keV
104
105
Ee = 500 keV• Measurement of Ee and tp for each event
B k d i th h i id f l t d
0 kV
0.00 0.02 0.04 0.06 0.081/tp
2 [1/μs2]
103
10Ee = 700 keV • Background suppression through coincidences of electron and
proton.
• Long flight path improves spectrometer
Determination of pp through tp: The magnetic field
30 kV p
||pz
SegmentedSi detector
TOF regionMagnetic Field
abat
ic
ersi
on
x
magnetic filterregion (field B0)
g(field rB·B0)
Proton Trajectory
Adi
aco
nv
z
decay volume (field rB,DV·B0)
0 kV
p
||p
x
0 kV
0 kV
Neutronbeam z • Measurement of Ee and tp for each
event
• Background suppression through 0 kV
x
g pp gcoincidences of electron and proton.
• Long flight path improves spectrometer
Silicon detector for Nab / abBA / PANDA
Front side Back side
Segmented ion-implanted silicon detector with fast readout electronics:
• Thickness 2 mm (less for testing)
• Thin dead layer of < 100 nm silicon (measured!):• Thin dead layer of < 100 nm silicon (measured!):
Energy loss for 30 keV protons: < 11 keV (measured!)
• 127 channels
Sufficiently small count rate/pixel,
Allows to find electron and correlated proton.
Detector properties: proton response
Proton beam, 32 keV, 50 s-1
Detector thickness: 500 μm
Detector properties: proton spectrum (II)ld 103
104
105
average energyloss: 11 keVThreshold?
Worst case simulation (dead layer: 100 nm Si)
Energy calibration: Si 1.0mm detector
Yie
l
101
102
103
Energy calibration: Si 1.0mm detector
Cd-109 dataProton data75
10
deposited Ep [keV] (w/o electronic noise)0 5 10 15 20 25
E (k
eV)
50Threshold lost protons efficiency slope
8 keV 0.19% 110(30) ppm/keV10 keV 0.20% 131(31) ppm/keV12 k V 0 21% 165(32) /k V
25 dead layer: 65 nm(but pulse heightdefect neglected)
12 keV 0.21% 165(32) ppm/keV14 keV 0.28% 304(76) ppm/keV
channels0
0100 200 300
For uncertainty in a, we assume a threshold of 10 keV and direct measurement of efficiency slope to 50%.
Electron energy measurement with backscattering suppression
30 kV10 4
10 5
detected Ee for e- in lower detector
detected Ee with only lower detector
D t t fSegmentedSi detector
TOF region
Yie
ld
10 1
10 2
10 3 Detector response forincoming Ee = 300 keV
magnetic filterregion (field B0)
g(field rB·B0)
detected Ee [keV]
1
10
0 50 100 150 200 250 300
decay volume (field rB,DV·B0)
0 kV
e [ ]
1000incoming Ee = 300 keV0 kV
0 kV
Neutronbeam
Yie
ld
10
100
0 kV
electron TOF between detectors [ns]
1
0 50 100 150-50-150 -100
Electron energy measurement with backscattering suppression
30 kV10 4
10 5
detected Ee for e- in lower detector
detected Ee with only lower detector
D t t fSegmentedSi detector
TOF region
Yie
ld
10 1
10 2
10 3 Detector response forincoming Ee = 300 keV
magnetic filterregion (field B0)
g(field rB·B0)
detected Ee [keV]
1
10
0 50 100 150 200 250 300
decay volume (field rB,DV·B0)
0 kV • Measurement of Ee (and tp) for each event
e [ ]
0 kV
0 kV
Neutronbeam
e ( p)
• Backscattering suppression through adding energies of both detectors.
• Reconstructing of electron energy needs 0 kV g gytime resolution of < 20 ns
Detector properties: Speed
Extraction of a in Nab
2ep
e
1 cos epa pE
A.U
.]
p p2
dist
ribut
ion
2pcos 1e p
2pcos 1e p
late
d co
unts
[A
Ee = 300 keV0.0 0.5 1.0 1.5
Ee = 550 keV
Sim
ul Ee = 500 keVEe = 700 keV
pp2 [MeV2/c2]
0.002 0.004 0.00601/tp
2 [µs-2]
Data analysis: Use edge to determine or verify the shape of the detection function
pp
p pcos ( )m dztp zq
= ò
shape of the detection function.
Then, use central part to determine slope and the correlation coefficient a.
Detailed spectrometer magnet design0.50
37.5014.7525.90
c1i
z
c1o eld
[T]
B
3
4
5
B (on axis)
Si detector
0.03
25.28 43.81
481.25
c1ic1o
Mag
netic
f ie
1
2
Bz (on axis)
Decayvolume
4 m flight path is omitted here466.25
5.00
4.34
10.5220.5838.16
29 94
3.193.28
4.9312.92
8 00
16.77 rc4i
c3ic2i
c4o
c3oc2o
M
z [m]0 0 1-1 2 3 4 5
5Filter
41.66
4.343.13
3.13
29.9416.4130.24
8.00c5ic5o
cfie
ld[ T
]B
2
3
4 Decayvolume
Filter
67.0914.7725.90
0 20-20 10-10-30
Bz (on axis)Bz (off axis)M
agne
tic
0
1
2
0.47
c6ic6o z [cm]
Nab setup, about to scale
B
Passive Antimagnetic Shield200cm
300cm
Top view:
Beam shutter
Beam stop
Beam pipe
200cm
Beam shutter
Spectrometer magnetNeutron guide
Side view: Detector supportt
Magnet Pit
Prototype detector spectra
Source: Cd 109. Preamp: LANL homemade. Micron detector, thickness: 1.5 mm
18.5 keV e-
62.5 keV e-
84.2,87.3,87.9 keV e-
Kelvin Probe: Tool to measure Work Functions
VMaterial 1 Material 2
Φ2 Φ2
Material 1 Material 2 Material 1 Material 2
VC
Φ1
EF,1
2
EF,2Φ1 Φ2 Φ1
EF 1 EF 2
EF,2
EF 1
VC
___
+++
+
F,1 F,2 F,1
VBias = -VC
2 M t i l ith diff t
Electrical Connection:
→ Charging, until Fermi Bi V lt2 Materials with different
work functions, isolated
1st material: to be tested
2nd t i l ti ith k
g g,levels are equal
→ External electric field
→ If Material 2 is moved:
Bias Voltage
→ Charge disappears, no external electric field
N t if M t i l 2 i2nd material: tip with known work function
Capacitance changes, voltage is constant, therefore charge has to change (current)
→ No current if Material 2 is moved
Kelvin Probe: First results from early work on aSPECT
Work Function [meV]
30
35
404900
[ ]
20
25
30ht
[mm
]4950
5000
5
10
15Hei
gh 5000
5050
0 50 100 150 200 250 300 3500
5
Angle [°]
5100
g [ ]
In collaboration with Prof. I. Baikie, KP Technologies
Now: Better coating
Work Function [meV]
303540
4900
15202530
Hei
ght [
mm
]
4950
5000 (arbitrary offset added)
16
0 50 100 150 200 250 300 35005
1015H
5050
5100
8
12
ight
[mm
]0 50 100 150 200 250 300 350Azimuth angle [°]
5100
In collaboration with Prof. I. Baikie, KP Technologies
0
4H
ei
0 4 8 120
Width [mm]Thanks to:Rachel Hodges (undergraduate research prize), Gertrud Konrad, Sean McGovern (Masters), Henry Bonner
Uncertainty budgetPLANNED systematic uncertainty budget:i i l i b d PLANNED systematic uncertainty budget:PLANNED statistical uncertainty budget:
lower Ee cutoff none 100 keV
100 keV
300 keV
Experimental parameter Systematic uncertainty Δa/a
Magnetic fieldcurvature at pinch 5 10 4
upper tp cutoff none none 40 μs 40 μs
Δa 2.4/√N 2.5/√N 2.5/√N 2.6/√N
Δa (Ecal, l 2 5/√N 2 6/√N 2 7/√N 2 7/√N
... curvature at pinch 5·10-4
… ratio rB = BTOF/B0 2.5·10-4
… ratio rB,DV = BDV/B0 3·10-4
Length of the TOF region (*)Electrical potential inhomogeneity:variable) 2.5/√N 2.6/√N 2.7/√N 2.7/√N
Δa (Ecal, lvariable, inner 70% of data)
4.1/√N 4.1/√N 4.1/√N 4.1/√N
Electrical potential inhomogeneity:… in decay volume / filter region 5·10-4
… in TOF region 1·10-4
Neutron Beam:position 4·10-4
About 2×109 events can be detected in 6 weeks (Decay volume V = 246 cm3, decay density n = 20 cm-3 12 7 % of decay protons
… position 4 10… profile (including edge effect) 2.5·10-4
… Doppler effect smallUnwanted beam polarization can be made smallAdiabaticity of proton motion 1·10-4density nd = 20 cm 3, 12.7 % of decay protons
go to upper detector, 80% duty factor)
→ (Δa/a)stat < 1×10-3 can be reached
Adiabaticity of proton motion 1 10Detector effects:… Electron energy calibration (*)… Electron energy resolution 5·10-4
… Proton trigger efficiency 2.5·10-4
Compare to Δa/a = 5 % of existing experimental results
gg yResidual gas smallBackground smallAccidental coincidences smallSum 1·10-3
Other ongoing experiments: aSPECT
i fi ld y ra
te w
(E)
Magnetic field
Protondetector
Analyzing PlaneB 0 314 T and for a = -0.103 (PDG 2006)
Dec
ay
Proton spectrum for a = +0.3
Superconducting
Retardationvoltage U
•+
•+
•+
•+
detectorBA = 0.314 T0 200 400 600
( )
Proton kinetic energy E [eV]
magnet
ProtonsDecayVolume= 1.55 TB0
Mirror voltageNeutrons
•+
•+
•+
•+
Leading uncertainty probably trapped particle background, (Δa/a)background = 0.61%
Other ongoing experiments: aCORN @ NIST
solenoid
Bproton
electroncollimator
electron
decay volume
+Vneutronbeam
protondetector proton
collimator
electrondetector
] l t t
4Simulated Data
pe
pp
pν
ton
TOF
[s]μ late protons
3
2Expected total uncertainty of Δa/a ~ 1 %
(limited by systematics)
l t f th il bl t dpr
ot6008004002000
early protons2
180-300 keV
• only part of the available neutron decays used
• I find it hard to determine the acceptance i l
beta kinetic energy [keV]
precisely
The determination of the Fierz Interference term
2 ee
e
1 3 1 mdw E bE
Electron spectrum:
e
Systematic uncertainties: nits
)
Sy1. Electron energy determination
Yie
ld(a
rb.u
n
b = +0.1SM104
105
Detector response to decay
Y SM
Yie
ld
102
103
electron with Ee = 300 keV
0 200 400 600 800Ee,kin (keV)
2% of events in tail(deadlayer,external bremsstrahlung)1
101
0 50 100 150 200 250 300
Δb ~ 3×10-3 can be reached (systematics limited)
2. Background
detected Ee [keV]
A/B at SNS or NIST: abBA / Nab / PANDA
Segmented Si detector
• A: reflect all protons to bottom detector, use top detector for electrons
TOF region (field rB·B0)
S iAFPSpin
3He
• B: detect protons at top
decay volume (field rB,DV·B0)
Supermirror(3He)
SpinFlipper
PolarimeterAFP
• Main uncertainties in PERKEO II: statistics, detector, polarization, background
• Superior detector energy resolution, good enough time resolution
K i id t i b k d• Keep coincidences to improve background
• Asymmetric detector: Filter improves on systematics; statistics @ SNS is an issue for A
• Polarization measurement seems manageable (XSM or He-3)
Uncertainty budget for APLANNED t ti t i t b d tPLANNED systematic uncertainty budget:PLANNED statistical uncertainty budget:
Experimental parameter Systematic uncertainty ΔA/ARelevant only for
lower Ee cutoff none100 keV
200 keV
250 keV
∆A 4.3/√N 4.8/√N 7/8/√N 11.9/√N
Nd is the number of decays. Only 13% are detected, due to asymmetric configuration.
Electrical potential inhomogeneity:y
B/CNeutron Beam:… position irrelevant… profile (including edge effect) small
D l ff ll
∆A 4.3/√N 4.8/√N 7/8/√N 11.9/√N
Nd = 2×109 decay events (40 live days at SNS)→ (ΔA/A)stat = 1×10-3 can be reached
ibl i
… Doppler effect small… Beam polarization < 10-3
Detector effects:… Electron energy calibration 2·10-4
… Electron energy resolution smallPossible improvements:• He3?• NIST NG-C?
… Electron energy resolution smallResidual gas smallBackground smallSum TBD
3Our goal is a total uncertainty of ΔA/A = 10-3 or better (same for B/C, not discussed)
Competition:
• UCNA: Goal ΔA/A = 2·10-3 (A. Young, NSAC), check of cold beam experimentsUCNA: Goal ΔA/A 2 10 (A. Young, NSAC), check of cold beam experiments
• UCNB: Goal ΔB/B = 10-3 , but electric potential homogeneities have to be ΔU < 0.3 mV
• PERC: Goal ΔA/A = 3·10-4
Time schedule
As presented at NSAC meeting,
assuming NO major technical or funding delays
2011 2012 2013 2014 2015 2016 2017 2018
design
Procurement, fabrication, optimization
installation and data takingtaking
switchover
data takingg
Nab abBA / PANDA
The experiment might move to NIST NG-C, probably for the polarized program.
Sensitivity to left-handed S-T couplings
“present limits”( )
muon decay
neutron and nuclear decays(survey, 68% C.L.)
(68% C.L.)“90% C.L.”
superallowed0?0 d++l d 0?0 decays(68% C.L.)
nuclear decays((In), 90% C.L.)P 107
Present limits (n decay data)SM is in the origin of this plot
Future limits,assuming a = -0.1059(1), A = -0.1186(1) ,B = 0.9807(30), C = -0.23785(24), τn = 882 2(13) s b = 0±0 003882.2(13) s, b 0±0.003
Model-dependent predictions: Supersymmetry, leptoquarks, …
Analysis similar to G. Konrad, S.B. et al., ArXiv:1007.3027
Sensitivity to right-handed S-T couplings
Present limits (n decay data)SM is in the origin of this plot
Future limits,assuming a = -0.1059(1), A = -0.1186(1) ,B = 0.9807(30), C = -0.23785(24), τn = 882.2(13) s0.9807(30), C 0. 3785( ), τn 88 . ( 3) s
Analysis similar to G. Konrad, S.B. et al., ArXiv:1007.3027
The Nab collaboration
R. Alarcona, L.P. Alonzib , S.B.b (Experiment Manager), S. Balascutaa, J.D. Bowmanc (Co-Spokesmen), M.A. Bychkovb, J. Byrned, J.R. Calarcoe, T.V. Ciancioloc, C. Crawfordf, E. Frležb, M.T. Gerickeg, F. Glückh, G.L. Greenei, R.K. Grzywaczi, V. Gudkovj, F.W. Hersmane, A. Kleink, J. Martinl, S. McGovernb, S. Pageg, A. Palladinob, S.I. Penttiläc (On-site Manager), D. PočanićcJ , S G , S g , , S (O g ),(Co-Spokesmen), K.P. Rykaczewskic, W.S. Wilburnk, A.Youngm
a Department of Physics, Arizona State University, Tempe, AZ 85287-1504b Department of Physics, University of Virginia, Charlottesville, VA 22904-4714c Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831d Department of Physics and Astronomy, University of Sussex, Brighton BN19RH, UKe Department of Physics, University of New Hampshire, Durham, NH 03824f Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506g Department of Physics, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canadah IEKP, Universität Karlsruhe (TH), Kaiserstraße 12, 76131 Karlsruhe, Germanyi Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996j Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208kk Los Alamos National Laboratory, Los Alamos, NM 87545l Department of Physics, University of Winnipeg, Winnipeg, Manitoba R3B2E9, Canadam Department of Physics, North Carolina State University, Raleigh, NC 27695-8202
Tasks of UVa group: Spectrometer design, Superconducting magnet, Proton source
Summary
• Precise and reliable results from neutron physics are preferred to extract information about the Standard Model withoutto extract information about the Standard Model without nuclear structure uncertainties
• Main difference to European effort (PERKEO II/III, aSPECT, p ( , ,PERC): less count rate, e--p coincidences
• Status of Nab spectrometer: Funding application at DOE to perform Nab at the FNPB beamline at the SNS. Second funding application to NSF (MRI)
E i i i d ( li i ) d f NSAC• Experiment is received (preliminary) endorsement of NSAC last week (rank 4 out of 5 out of 15)
Thank you for your interest !!