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New signals and old backgrounds in dark matter direct detection - - PowerPoint PPT Presentation

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New signals and old backgrounds in dark matter direct detection Josef Pradler Perimeter Institute with Spencer Chang and Itay Yavin , Phys.Rev.D 85 063505 (2012) with Maxim Pospelov , arXiv:1203.0545 CERN, March 16, 2012 Friday, 16 March, 12

slide-1
SLIDE 1

New signals and old backgrounds in dark matter direct detection

Josef Pradler Perimeter Institute

with Spencer Chang and Itay Yavin, Phys.Rev.D 85 063505 (2012) with Maxim Pospelov, arXiv:1203.0545 CERN, March 16, 2012

Friday, 16 March, 12

slide-2
SLIDE 2
  • dark matter vs. neutrinos from the sun
  • “baryonic” neutrinos
  • direct detection experiments as observatories?

νb νb Part I

  • signal modulation in dark matter direct detection experiments
  • DAMA & CoGeNT and the “muon-hypothesis”
  • new signatures from dark matter modulation

Part II

PLAN

Friday, 16 March, 12

slide-3
SLIDE 3
  • DAMA: 250 kg of scintillating NaI crystals, running since

1995, exposure in excess of 1 ton x year, no discrimination

  • CoGeNT: 440 g Ge crystal, 442 live days; ionization only, no

discrimination

  • CRESST: scintillation and phonons; 730 kg days, multi-target
  • ne

species

  • three

signals?

Friday, 16 March, 12

slide-4
SLIDE 4

[Angloher et al., 2011]

  • DAMA: 250 kg of scintillating NaI crystals, running since

1995, exposure in excess of 1 ton x year, no discrimination

  • CoGeNT: 440 g Ge crystal, 442 live days; ionization only, no

discrimination

  • CRESST: scintillation and phonons; 730 kg days, multi-target
  • ne

species

  • three

signals?

Friday, 16 March, 12

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SLIDE 5

Part I

“take away message”

  • cosmic muons as origin for DAMA modulation strongly disfavoured
  • different in phase
  • different in correlation
  • possibly different in power
  • possibly different in amplitude
  • similar conclusions hold for CoGeNT modulation
  • there is more than “one modulation”

Friday, 16 March, 12

slide-6
SLIDE 6

signal modulation in direct detection

[cpd/kg/keV]

dR dER = NT nDM Z

v≥vmin

d3v vfLAB(v) dσ dER fGAL(vobs + v)

see e.g. [Druiker et al, 1986; Freese et al, 1988; Savage et al, 2009]

Friday, 16 March, 12

slide-7
SLIDE 7

signal modulation in direct detection

[cpd/kg/keV]

dR dER = NT nDM Z

v≥vmin

d3v vfLAB(v) dσ dER fGAL(vobs + v)

|vobs| = |v| + 1 2V cos ω(t − t0)

t0 ' 152 days (June 2nd)

vobs = v + V [ε1 cos ω (t − t1) + ε2 sin ω (t − t1)]

see e.g. [Druiker et al, 1986; Freese et al, 1988; Savage et al, 2009]

Friday, 16 March, 12

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SLIDE 8

signal modulation in direct detection

t0 ' 152 days (June 2nd)

c1 c0 . vmin (km/s) |cn| (km/s)−1 800 700 600 500 400 300 200 100 10−2 10−3 10−4 10−5 10−6 10−7 10−8 10−9 10−10

dR(t) dER / Z ∞

vmin

f(v) v dv ' c0(vmin) + c1(vmin) cos [ω(t t0)]

vmin = 1 √2mNER ✓mNER µNχ + δ ◆

annual modulation

[using f(v) from Lisanti et al, 2010]

Friday, 16 March, 12

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SLIDE 9

(2–6 keV) days since Jan 1, 1995 5000 4500 4000 3500 0.04 0.02

  • 0.02
  • 0.04

(2–5 keV) residuals (cpd/kg/keV) 0.04 0.02

  • 0.02
  • 0.04

DAMA/LIBRA 0.87 ton×yr (2–4 keV) 0.04 0.02

  • 0.02
  • 0.04
  • scintillation from

NaI-crystals

  • 8σ+ modulation
  • phase consistent

as expected from WIMPs

t0 ' 2 June

∼ 3%

[Bernabei et al. 2010]

= 152.5 days

Friday, 16 March, 12

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SLIDE 10

Muon Flux underground

  • underground flux sourced mainly by primary meson decays (pions,

kaons,...) => muons need to be TeV-like to reach underground

  • competition between secondary meson interactions vs. decay

depends on air-density => muon flux correlated with temperature

  • flux peaks in Summer (on northern hemisphere)

∆Iµ I0

µ

= αT ∆Teff Teff Teff = Z ∞ dX T(X)W(X)

  • -- modulates too ---

Friday, 16 March, 12

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SLIDE 11

Muon Flux underground

  • many measurements available, correlation

with firmly established

  • LNGS: Macro, LVD,

Borexino (DAMA location)

  • Soudan Mine: MINOS

(CoGeNT location)

  • South Pole: Amanda,

Icecube

Teff Teff

φµ

[Borexino 2011]

Friday, 16 March, 12

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SLIDE 12

LVD and DAMA

  • Large

Volume liquid scintillator Detector (LVD) reports underground muon-flux at LNGS => temporal overlap with DAMA data

[Selvi, 2009]

Iµ ∼ 30/day/m2

@ DAMA site

Friday, 16 March, 12

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SLIDE 13

(digitized from LVD data) t (days) muon flux (10−7cm−2 s−1) 2500 2000 1500 1000 500 0.37 0.36 0.35 0.34 0.33 0.32 0.31 0.3

LVD and DAMA

  • renewed interest in muons as DAMA background, see e.g.

[Ralston, 2010], [Nygren, 2011], [Blum, 2011]

  • very recent response by DAMA [Bernabei, 2012]

Friday, 16 March, 12

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SLIDE 14

LVD and DAMA

muons 2–4 keV . days since Jan 1, 2001 percent residuals 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 6 4 2

  • 2
  • 4
  • 6
  • renewed interest in muons as DAMA background, see e.g.

[Ralston, 2010], [Nygren, 2011], [Blum, 2011]

  • very recent response by DAMA [Bernabei, 2012]

Friday, 16 March, 12

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SLIDE 15

LVD and DAMA

  • muons can either directly hit the detector or indirectly, by spallation
  • f nuclei which leads to neutron flux

=> guaranteed source of background (especially if un-vetoed)

  • in this talk we will base our analysis exclusively on the time-series of

events in both data sets => we are ignorant to how the signal formation process concretely happens => but if we can make firm statements already it means that this approach is very model-independent and thus conservative

Friday, 16 March, 12

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SLIDE 16
  • evenly spaced data discrete FT
  • unevenly spaced data: Lomb-Scargle Periodogram

detecting periodicities

˜ ti ≡ ti − τ

P(ω) ∝

  • X

i

di exp(−iωti)

  • 2

= 2 4 X

i

di cos(ωti) !2 + X

i

di sin(ωti) !23 5

di = d(ti)

  • invariant to shifts in

time origin

  • if is pure noise (with

unit variance)

di Pr(P > p) = e−p

LS(ω) = 1 2 8 < : 1 P

i cos2

ω˜ ti

  • "X

i

di cos

  • ω˜

ti

  • #2

+ 1 P

i sin2

ω˜ ti

  • "X

i

di sin

  • ω˜

ti

  • #29

= ;

Friday, 16 March, 12

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SLIDE 17

detecting periodicities

50 100 200 500 1000 2000 1 5 10 50 100 500 Period HdaysL Power

99% Hany freqL 99% Hone freqL T = 365 days

100 1000 500 200 2000 300 150 1500 700 0.5 1.0 5.0 10.0 50.0 Period HdaysL Power

99% Hany freqL 99% Hone freqL T = 365 days

DAMA/LIBRA LVD muons

no power on timescales > 1yr

Friday, 16 March, 12

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SLIDE 18

detecting periodicities

50 100 200 500 1000 2000 1 5 10 50 100 500 Period HdaysL Power

99% Hany freqL 99% Hone freqL T = 365 days

100 1000 500 200 2000 300 150 1500 700 0.5 1.0 5.0 10.0 50.0 Period HdaysL Power

99% Hany freqL 99% Hone freqL T = 365 days

DAMA/LIBRA LVD muons

adopting DAMA’s procedure of subtracting baseline on each cycle suppresses power on timescales longer than 1 yr (see also Blum, 2011) no power on timescales > 1yr BUT

Friday, 16 March, 12

slide-19
SLIDE 19

detecting periodicities

DAMA/LIBRA, 2012

2.5 5 7.5 10 12.5 15 17.5 20 22.5 0.001 0.002 0.003 0.00

6 years period

Frequency (d-1) Normalized Power

LS of baselines O(10) data points, no significant power!

Friday, 16 March, 12

slide-20
SLIDE 20

detecting periodicities

DAMA/LIBRA, 2012 LVD muons

2.5 5 7.5 10 12.5 15 17.5 20 22.5 0.001 0.002 0.003 0.00

6 years period

Frequency (d-1) Normalized Power

LS of baselines O(10) data points, no significant power!

1000 2000 1500 0.1 1 10 100 THdaysL LS

99% Hone freqL

LS of muon baselines O(10) data points no significant power neither!

Friday, 16 March, 12

slide-21
SLIDE 21

detecting periodicities

DAMA/LIBRA, 2012

2.5 5 7.5 10 12.5 15 17.5 20 22.5 0.001 0.002 0.003 0.00

6 years period

Frequency (d-1) Normalized Power

  • with a small dataset it is hard to

achieve statistical significance => normalized power

  • power spectrum of baselines

alone does NOT convincingly show that there is indeed no long term modulation in DAMA

P(ω) = LS(ω)/σ2

=> DAMA should provide baseline rates

Friday, 16 March, 12

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SLIDE 22

340 350 360 370 380 390 400 50 100 150 200 Period HdaysL Phase HdaysL

DAMAêLIBRA LVD 68% 90% 99%

The phase of DAMA vs the “phase” of LVD

A × cos [ω(t − t0)]

  • interpret data as sinusoidal

variations

  • phase of DAMA/LIBRA

incompatible with muons

t0(LVD) = (187 ± 2) days

DM

t0(DAMA) = (131 ± 13) days @ ω = 2π/1yr :

Friday, 16 March, 12

slide-23
SLIDE 23

The phase of DAMA vs the “phase” of LVD

  • two studies suggest that phase can potentially in agreement
  • 1. Selvi for LVD collaboration finds

Progressive day in year 50 100 150 200 250 300 350

−1

s)

2

Muon intensity (m 0.3 0.31 0.32 0.33 0.34 0.35 0.36 0.37

−3

10 ×

t0(LVD)LVD−collab = (185 ± 15) days

[Selvi for LVD, 2009]

χ2/dof = 577/362

adopting this procedure we find !

t0(LVD) = (186 ± 2) days

Friday, 16 March, 12

slide-24
SLIDE 24

The phase of DAMA vs the “phase” of LVD

  • two studies suggest that phase can potentially in agreement
  • 1. Selvi for LVD collaboration finds

Progressive day in year 50 100 150 200 250 300 350

−1

s)

2

Muon intensity (m 0.3 0.31 0.32 0.33 0.34 0.35 0.36 0.37

−3

10 ×

t0(LVD)LVD−collab = (185 ± 15) days

[Selvi for LVD, 2009]

χ2/dof = 577/362

adopting this procedure we find suspecting that Selvi used reduced for construction of confidence region => confidence interval overestimated !

χ2

↯

t0(LVD) = (186 ± 2) days

Friday, 16 March, 12

slide-25
SLIDE 25

The phase of DAMA vs the “phase” of LVD

  • two studies suggest that phase can potentially in agreement
  • 2. Blum, 2011:

nice observation that direct hits by muons induce produce too large spread in signal, BUT hNµ,ii = AeffIµ,iiti si = yNµ,i M∆Eiti Nµ,i mean of Poisson distributed count rate in DAMA bin i = signal counts / muon y

=> used to generate DAMA mock data

Friday, 16 March, 12

slide-26
SLIDE 26

The phase of DAMA vs the “phase” of LVD

  • two studies suggest that phase can potentially in agreement
  • 2. Blum, 2011:

nice observation that direct hits by muons induce produce too large spread in signal, BUT DAMA muons hNµ,ii = AeffIµ,iiti si = yNµ,i M∆Eiti y

=> used to generate DAMA mock data

Friday, 16 March, 12

slide-27
SLIDE 27

mock muons dama (2–4) keV . days since Jan 1, 2001 residuals (cpd/kg/keV) 3000 2500 2000 1500 1000 0.1 0.05

  • 0.05
  • 0.1

The phase of DAMA vs the “phase” of LVD

=> redo Blum’s analysis: (one representative out of a sample of 10k)

Friday, 16 March, 12

slide-28
SLIDE 28

[Blum, arXiv:1110.0857]

50 100 150 200 250 300 0.000 0.005 0.010 0.015 t0 HdaysL PDF

Mean = 187 S.D. = 27

The phase of DAMA vs the “phase” of LVD

vs.

Friday, 16 March, 12

slide-29
SLIDE 29

[Blum, arXiv:1110.0857]

50 100 150 200 250 300 0.000 0.005 0.010 0.015 t0 HdaysL PDF

Mean = 187 S.D. = 27

The phase of DAMA vs the “phase” of LVD

vs.

t0 from Jan 1, 2003 t0 from Jan 1,1995

Friday, 16 March, 12

slide-30
SLIDE 30

[Blum, arXiv:1110.0857]

50 100 150 200 250 300 0.000 0.005 0.010 0.015 t0 HdaysL PDF

Mean = 187 S.D. = 27

The phase of DAMA vs the “phase” of LVD

vs.

since period floats in fit => looses its absolute meaning! t0 t0 from Jan 1, 2003 t0 from Jan 1,1995

Friday, 16 March, 12

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SLIDE 31

lessons learned

  • 1. distribution in depends on time origin

=> frequentist fits to mock-data do not define a good test statistic

  • 2. we need better ways to quantify agreement/disagreement of

DAMA with the Muon hypothesis => preferentially without reliance on sinusoidal function => look at the correlation coefficient t0 r ∈ [−1, 1]

rXY = P

i(Xi − ¯

X)(Yi − ¯ Y ) qP

i(Xi − ¯

X)2 qP

i(Yi − ¯

Y )2

Friday, 16 March, 12

slide-32
SLIDE 32

correlation study

correlation r(muon,mock=DAMA) correlation r(muon,mock)

Q: how significant is the difference between these two?

Correlation coefficient r 1 0.5

  • 0.5
  • 1

0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02

Friday, 16 March, 12

slide-33
SLIDE 33

Correlation coefficient r 1 0.5

  • 0.5
  • 1

0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02

correlation r(muon,mock=DAMA) correlation r(muon,mock) Model excluded & 99% C.L.

0.6 0.8 1.0 1.2 1.4 1 2 3 4 Fisher Z Transform PDF

Mean = 0.95 S.D. = 0.13 Z = 0.47

correlation study

Friday, 16 March, 12

slide-34
SLIDE 34
  • 442 kg live-days
  • Ge-target, ionization
  • potential exponential rise

toward low energies

  • cosmogenic peaks
  • modulation too
  • GeNT
  • C

[Aalseth et al, 2011]

Friday, 16 March, 12

slide-35
SLIDE 35
  • muon measurements at CoGeNT site (Soudan Mine, MN) from

MINOS experiment exist

[Adamson et al, 2010]

  • GeNT
  • C

Friday, 16 March, 12

slide-36
SLIDE 36

phase analysis for CoGeNT

250 300 350 400 450 50 100 150 200 Period HdaysL Phase HdaysL

CoGeNT 0.5-3.0 keVee MINOS 68% 90%

Data has no temporal overlap!

Friday, 16 March, 12

slide-37
SLIDE 37
  • muon measurements at CoGeNT site (Soudan Mine, MN) from

MINOS experiment exist - but no temporal overlap

[Adamson et al, 2010]

  • GeNT
  • C

Friday, 16 March, 12

slide-38
SLIDE 38
  • muon measurements at CoGeNT site (Soudan Mine, MN) from

MINOS experiment exist - but no temporal overlap

MINOS time period, Teff = 221.44 K days since Oct 1, 2003 ∆Teff/Teff in % 1800 1600 1400 1200 1000 800 600 400 200 4 2

  • 2
  • 4

=> use available climate data to predict muon flux!

[Adamson et al, 2010]

  • GeNT
  • C

Friday, 16 March, 12

slide-39
SLIDE 39

vs.

CoGeNT MINOS published days since Dec 3, 2009 Teff (K) 500

  • 500
  • 1000
  • 1500
  • 2000
  • 2500

235 230 225 220 215 210 205 days since Dec 3, 2009 Teff (K) 500

  • 500
  • 1000
  • 1500
  • 2000
  • 2500

235 230 225 220 215 210 205

  • GeNT
  • C

“International Falls, MN” balloon data

Friday, 16 March, 12

slide-40
SLIDE 40

1.5–3.0 keV 0.9–1.5 keV 0.5–0.9 keV 0.5–3.0 keV 90% C.L. binsize (livedays) r 120 100 80 60 40 20 1 0.5

  • 0.5
  • 1

no correlation with high significance! => CoGeNT’s modulation not muon-induced

  • GeNT
  • C

correlation study

Friday, 16 March, 12

slide-41
SLIDE 41

higher harmonics in DM modulation

c1 c0 . vmin (km/s) |cn| (km/s)−1 800 700 600 500 400 300 200 100 10−2 10−3 10−4 10−5 10−6 10−7 10−8 10−9 10−10

vmin = 1 √2mNER ✓mNER µNχ + δ ◆

dR(t) dER / Z ∞

vmin

f(v) v dv ' c0(vmin) + c1(vmin) cos [ω(t t0)]

[using f(v) from Lisanti et al, 2010]

Friday, 16 March, 12

slide-42
SLIDE 42

c3 c2 c1 c0 k = 1.5 vmin (km/s) |cn| (km/s)−1 800 700 600 500 400 300 200 100 10−2 10−3 10−4 10−5 10−6 10−7 10−8 10−9 10−10

higher harmonics in DM modulation

vmin = 1 √2mNER ✓mNER µNχ + δ ◆

dR(t) dER ∝ Z ∞

vmin

f(v) v dv = X

n=0,1,...

cn(vmin) cos [nω(t − tn)]

  • biannual mode
  • triannual mode
  • ...

[using f(v) from Lisanti et al, 2010]

Friday, 16 March, 12

slide-43
SLIDE 43

n = 3 n = 2 k = 1.5 vmin (km/s) (tn − t1) (days) 800 700 600 500 400 300 200 100 50 40 30 20 10 −10 −20 −30 −40 −50 c3 c2 c1 c0 k = 1.5 vmin (km/s) |cn| (km/s)−1 800 700 600 500 400 300 200 100 10−2 10−3 10−4 10−5 10−6 10−7 10−8 10−9 10−10

higher harmonics in DM modulation

  • can be thought of as an

expansion in

  • nce ellipticity of earth’s
  • rbit is included

=> phase shifts between different harmonics => new signature

  • detection is likely to

require large exposure

V/v

Friday, 16 March, 12

slide-44
SLIDE 44

higher harmonics in DM modulation

  • can be thought of as an

expansion in

  • nce ellipticity of earth’s
  • rbit is included

=> phase shifts between different harmonics => new signature

  • detection is likely to

require large exposure

V/v

n = 3 n = 2

DAMA triannual u.l. biannual u.l.

k = 1.5 vmin (km/s) |cn/c1| 800 700 600 500 400 300 200 100 101 1 10−1 10−2 10−3 10−4

100 1000 500 200 2000 300 150 1500 700 0.5 1.0 5.0 10.0 50.0 Period HdaysL Power

99% Hany freqL 99% Hone freqL T = 365 days

Pobs(biann) = 0.57 Pobs(triann) = 1.8

DAMA/LIBRA:

Friday, 16 March, 12

slide-45
SLIDE 45

Part II

“moral”

  • there can be alternatives to the

“light WIMP paradigm” in explaining direct detection anomalies/signals => diversifying physics output of direct detection experiments [see e.g. also Harnik, Kopp, Machado 2012]

Friday, 16 March, 12

slide-46
SLIDE 46

Part II

“moral”

  • there can be alternatives to the

“light WIMP paradigm” in explaining direct detection anomalies/signals => diversifying physics output of direct detection experiments [see e.g. also Harnik, Kopp, Machado 2012]

[Angloher et al., 2011]

Friday, 16 March, 12

slide-47
SLIDE 47

Leo Stodolsky’s vision of a true neutrino observatory

  • superconducting grains in filler material in magnetic field
  • at low temperatures specific heat ~

=> single scatter of neutrino can make grain conducting => magnetic field collapses, induces electric signal in detector T 3

Friday, 16 March, 12

slide-48
SLIDE 48
  • coherent enhancement for MeV-scale neutrinos from

=> spallation sources, supernovae, reactors, sun, earth

  • cross section grows quadratically with neutrino energy
  • helicity conservation forbids back-scattering

coherent neutrino- nucleus scattering

N 2 dσ d cos θ = 1 8π G2

F E2 ν

⇥ Z(4 sin2 θW − 1) + N ⇤2 (1 + cos θ)

Friday, 16 March, 12

slide-49
SLIDE 49
  • coherent enhancement for MeV-scale neutrinos from

=> spallation sources, supernovae, reactors, sun, earth

  • cross section grows quadratically with neutrino energy
  • helicity conservation forbids back-scattering

coherent neutrino- nucleus scattering

N 2 dσ d cos θ = 1 8π G2

F E2 ν

⇥ Z(4 sin2 θW − 1) + N ⇤2 (1 + cos θ) (this process has not yet been observed)

Friday, 16 March, 12

slide-50
SLIDE 50

=> direct DM detection

Witten 1985

~ keV

Friday, 16 March, 12

slide-51
SLIDE 51

=> direct DM detection

  • nuclear recoil can be picked up in various channels:

heat ionization scintillation

Friday, 16 March, 12

slide-52
SLIDE 52

WIMPs vs. solar neutrinos

  • flux
  • cross section
  • recoil

ΦDM = ρ0v mDM ∼ 105 cm−2s−1 ✓100 GeV mDM ◆ Φpp = 6 × 1010 cm−2s−1 Φ8B = 6 × 106 cm−2s−1 σ ' 10−44 cm2 ⇥ N 2 ✓ Eν 1 MeV ◆2 σ = 10−44 cm2 × σ44A2 ✓µN µn ◆2 Emax

R

= (2µNv)2 2mN ⇠ 8 > > > > > < > > > > > : 20 keV A

20

  • (mN ⌧ mDM)

4 keV mDM

20 GeV

2 100

A

  • (mDM ⌧ mN)

Emax

R

= (2Eν)2 2mN ∼ 0.1 keV ✓20 A ◆ ✓ Eν 1 MeV ◆2

Friday, 16 March, 12

slide-53
SLIDE 53

solar as a future background

[Monroe 2007]

1 ton x year we are not too far away from this

ν

Friday, 16 March, 12

slide-54
SLIDE 54

“baryonic” neutrinos

  • M. Pospelov arXiv:1103.3261

νb

  • introduce new left-handed neutrino species

together with gauged

  • couples to quarks, but not to leptons
  • breaking of gives new gauge field mass

U(1)b νb U(1)b Vµ νb

sterile under SM-gauge group active under U(1)b

LB = νbγµ(i∂µ − glqbVµ)νb − 1 3gb X

q

¯ qγµqVµ − 1 4VµνV µν + 1 2m2

V VµV µ + Lm.

νb

Friday, 16 March, 12

slide-55
SLIDE 55

“baryonic” neutrinos

  • M. Pospelov arXiv:1103.3261

νb

  • for effective Lagrangian reads
  • measure interaction strength in units of :

jµ

NCB = νbγµνb

Q2 ⌧ m2

V

GF Leff = −GBjµ

NCB

X

N=n,p

NγµN, GB = qb gbgl m2

V

N = |GB| GF ⇥ 100 ✓3 GeV mV ◆2 ✓ glgb 10−2 ◆

Friday, 16 March, 12

slide-56
SLIDE 56

“baryonic” neutrinos

  • M. Pospelov arXiv:1103.3261

νb

  • baryonic neutrino can get mass from
  • neutrinos talk via mass mixing => “sterile-active” oscillations

nkL = X

α

U ∗

kαναL,

U = 1 2 3 4 e µ τ b B B @ · UPMNS · · · · · · 1 C C A Lm = 1 2N T

L C†MNL + h.c.,

NL =   ν

b

ν

L

νC

R

  , M =   0T vbbT mT

D

vbb mD mR   νR

Friday, 16 March, 12

slide-57
SLIDE 57

“baryonic” neutrinos

  • M. Pospelov arXiv:1103.3261

νb

  • crucial insight:
  • deuteron breakup in SNO does not constrain scenario

σνbN(elastic) σνbN(inelastic) ∼ A2 E4

νR4 N

∼ O(108) this ratio makes direct detection experiments competitive with large scale neutrino experiments

Friday, 16 March, 12

slide-58
SLIDE 58

matter effects

  • forward scattering induces matter potential

VNCB = ±qbNGF nB (YN + 2Yνb) , Yf = nf − nf nB , VNCB : VCC : VNC = qbN : √ 2Xp : − √ 2(1 − Xp)/2,

mass fraction of protons => experience largest effect in normal matter for

Xp = νb N 1

Friday, 16 March, 12

slide-59
SLIDE 59

matter effects

  • flavor transition amplitudes from Schrödinger eq.

matter mixing angle => mixing angle in matter suppressed for ∆m2

b cos 2θb ⇥ 10−4 eV2

✓ E 10 MeV ◆ ✓ N 100 ◆ ✓ ρ g/cm3 ◆ tan 2θM = tan 2θb 1 + 2EVNCB/(∆m2

b cos 2θb)

i d dx ✓ ψαα ψαb ◆ ' 1 4E ✓ ∆m2

b cos 2θb 2EVNCB

∆m2

b sin 2θb

∆m2

b sin 2θb

∆m2

b cos 2θb + 2EVNCB

◆ ✓ ψαα ψαb ◆

Friday, 16 March, 12

slide-60
SLIDE 60

matter effects

  • considering such small values in

standard solar story unfolds

∆m2

b

Pb(earth) ' sin2(2θb) sin2 ∆m2

bL(t)

4E

  • N 2

eff ≡ N 2

2 × sin2 2θb

=> for fast oscillations PbG2

B → N 2 effG2 F

(from a tribimaximal ansatz assuming mixing to ) ν2 [see arXiv:1103.3261]

Friday, 16 March, 12

slide-61
SLIDE 61

direct detection of

dR(t) dER = NT  L0 L(t) 2 X

i

Φi Z

Emin

ν

dEν d fi dEν dσ dER Pb(t, Eν)

  • verall flux

modulation average over neutrino spectrum i

L(t) = L0 ⇢ 1 − cos 2⇥(t − t0) 1 yr

  • L0 = 1 AU

t0 ' 3 Jan (perihelion) = 0.0167 (eccentricity)

νb

like SM-neutrinos with G2

F (N/2)2 → G2 BA2

Friday, 16 March, 12

slide-62
SLIDE 62

17F 15O 13N

pp hep

8B

Silicium ER [keV] recoil spectrum [events/keV/kg-d] 10 1 0.1 0.01 108 107 106 105 104 103 102 101 1

17F 15O 13N

pp hep

8B

Eν [MeV] solar ν flux [cm−2s−1MeV−1] 10 1 0.1 1012 1010 108 106 104 102 1

ASi = 28 Neff = 100

direct detection of νb

(perfect detector)

Friday, 16 March, 12

slide-63
SLIDE 63

17F 15O 13N

pp hep

8B

Germanium ER [keV] recoil spectrum [events/keV/kg-y] 10 1 0.1 0.01 108 107 106 105 104 103 102 101 1

17F 15O 13N

pp hep

8B

Eν [MeV] solar ν flux [cm−2s−1MeV−1] 10 1 0.1 1012 1010 108 106 104 102 1

AGe = 70 − 76

8B

Neff = 100

direct detection of νb

(perfect detector)

Friday, 16 March, 12

slide-64
SLIDE 64

dR(t) dER = NT  L0 L(t) 2 X

i

Φi Z

Emin

ν

dEν d fi dEν dσ dER Pb(t, Eν)

more modulation here

Losc L0 ' 0.5 ⇥ ✓10−10 eV ∆m2 ◆ ✓ Eν 10 MeV ◆

  • scillation-length on the
  • rder sun-earth distance

=> flip phase for high energy part of the neutrino spectrum? explain DAMA?

direct detection of νb

Friday, 16 March, 12

slide-65
SLIDE 65

∼ 3%

  • DAMA signal conveniently expressed in terms modulation

amplitude S = S0 + Sm cos [ω(t − t0)] Sm = 1 2 ✓ dR dEv

  • max

− dR dEv

  • min

◆ Sm S0 ∼ 1 cpd/kg/keV (baseline) Sm/S0 ∼ 3%

Friday, 16 March, 12

slide-66
SLIDE 66

νb DAMA 2010

χ2/d.o.f. = 9.3/8 ∆m2 = 2.52 × 10−10 eV2 Neff = 102 . Ev [keVee] modulation amplitude (cpd/kg/keVee) 20 15 10 5 0.03 0.025 0.02 0.015 0.01 0.005

  • 0.005
  • 0.01

∼ 3%

fit only first 10 bins

Friday, 16 March, 12

slide-67
SLIDE 67

∼ 3%

N 2

eff ≡ N 2

2 × sin2 2θb

99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10 DAMA 99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10

Friday, 16 March, 12

slide-68
SLIDE 68

νb DAMA 2010

χ2/d.o.f. = 9.3/8 ∆m2 = 2.52 × 10−10 eV2 Neff = 102 . Ev [keVee] modulation amplitude (cpd/kg/keVee) 20 15 10 5 0.03 0.025 0.02 0.015 0.01 0.005

  • 0.005
  • 0.01

∼ 3%

used Q = 0.3

Friday, 16 March, 12

slide-69
SLIDE 69

∼ 3%

  • Q = quenching factor

scintillation light (L) output depends on the stopping power of the scattered nucleus dL dx = AdE/dx 1 + kBdE/dx (Birk’s formula) L ⇠ A 1 + kBhdE/dxi Z ER dE Ev(keVee) = Q × ER(keV) (Q can be energy dependent)

Friday, 16 March, 12

slide-70
SLIDE 70
  • new quenching factor

measurements indicate smaller values => higher nuclear recoil energy necessary to produce same

  • bserved signal in scintillation

(for DM this means larger WIMP masses; moves light-DM DAMA region deeper into “forbidden” zone)

[Collar, TAUP talk 2011]

∼ 3%

Friday, 16 March, 12

slide-71
SLIDE 71
  • new quenching factor

measurements indicate smaller values => higher nuclear recoil energy necessary to produce same

  • bserved signal in scintillation

(for DM this means larger WIMP masses; moves light-DM DAMA region deeper into “forbidden” zone)

[Collar, TAUP talk 2011]

∼ 3%

Friday, 16 March, 12

slide-72
SLIDE 72

99% C.L. ∆m2 [eV2] Neff 10−9 10−10 1000 100 10 DAMA QNa = 0.15 DAMA 99% C.L. ∆m2 [eV2] Neff 10−9 10−10 1000 100 10

∼ 3%

N 2

eff ≡ N 2

2 × sin2 2θb

Friday, 16 March, 12

slide-73
SLIDE 73

∼ 3%

phase off by ~month!

(2–6 keV) days since Jan 1, 1995 5000 4500 4000 3500 0.04 0.02

  • 0.02
  • 0.04

(2–5 keV) residuals (cpd/kg/keV) 0.04 0.02

  • 0.02
  • 0.04

DAMA/LIBRA 0.87 ton×yr (2–4 keV) 0.04 0.02

  • 0.02
  • 0.04

Friday, 16 March, 12

slide-74
SLIDE 74
  • 442 kg live-days
  • Ge-target, ionization
  • exponential rise

toward low energies!

  • cosmogenic peaks
  • indication of modulation
  • GeNT
  • C

[Aalseth et al, 2011]

Friday, 16 March, 12

slide-75
SLIDE 75
  • 442 kg live-days
  • Ge-target, ionization
  • exponential rise

toward low energies

  • cosmogenic peaks

subtracted

  • will not address

modulation here!

  • GeNT
  • C

const νb νb+const L-shell bkg. subtracted CoGeNT 442 days

∆m2 = 1.76 × 10−10 eV2 Neff = 228 Ev [keVee] events / 0.1 keVee 3 2.5 2 1.5 1 0.5 250 200 150 100 50

Friday, 16 March, 12

slide-76
SLIDE 76

99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10 DAMA CoGeNT 99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10

  • GeNT
  • C

Friday, 16 March, 12

slide-77
SLIDE 77
  • additional surface

background

  • rise at lowest

recoil energies near threshold will be revised

  • for DM this

means smaller cross sections

  • GeNT
  • C

[Collar, TAUP talk 2011]

Friday, 16 March, 12

slide-78
SLIDE 78
  • additional surface

background

  • rise at lowest

recoil energies near threshold will be revised

  • for DM this

means smaller cross sections

  • GeNT
  • C

[Collar, TAUP talk 2011]

Friday, 16 March, 12

slide-79
SLIDE 79
  • GeNT
  • C

allow for exponential background in the fit (everything below the line then fits the data)

99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10 CoGeNT hull DAMA CoGeNT 99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10

Friday, 16 March, 12

slide-80
SLIDE 80

constraints: XENON100

  • 100.9 live-days x 48 kg fiducial;
  • 3 events in acceptance region; use “maximum gap” method to set limit
  • require S1 ≥ 4PE’s (scintillation); account for quality and ER rejection

cuts; smear with Poissonian resolution

  • use extrapolated to 0 at 2keV

Leff

S1(ER) = 3.6 PE × ER × Leff

[Aprile et al. 2010]

Friday, 16 March, 12

slide-81
SLIDE 81

1 2 4 8 16 32 64

nuclear recoil energy Enr [keV] S2 width σe [µs]

0.5 1 2 5 10 20 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45

10 < z ≤ 15 cm 0 < z ≤ 5 cm

dN/dσe 50 100150

constraints: XENON10 low thr.

  • discard scintillation signal => buys e-background, wins lower threshold
  • ionization only (S2)
  • use
  • include Poisson

[Aprile et al. 2011]

S2 = QyERζ

{

ne

(large uncertainty in number of ionized electrons [Collar, 2011])

Emin = 1.4 keV => resulting bounds uncertain

Friday, 16 March, 12

slide-82
SLIDE 82

1 2 4 8 16 32 64

nuclear recoil energy Enr [keV] S2 width σe [µs]

0.5 1 2 5 10 20 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45

10 < z ≤ 15 cm 0 < z ≤ 5 cm

dN/dσe 50 100150

constraints: XENON10 low thr.

  • discard scintillation signal => buys e-background, wins lower threshold
  • ionization only (S2)
  • use
  • include Poisson

[Aprile et al. 2011]

1 10 100 1 2 3 4 5 6 7 8 9 10 nuclear recoil energy Enr [keV] Qy [electrons/keV]

  • Eq. 1, k = 0.166
  • Eq. 1, k = 0.110

[32], Ed = 0.73 kV/cm [18], Ed = 1.00 kV/cm [31], Ed = 2.00 kV/cm [31], Ed = 0.10 kV/cm

S2 = QyERζ

{

ne

(large uncertainty in number of ionized electrons [Collar, 2011])

Emin = 1.4 keV => resulting bounds uncertain

Friday, 16 March, 12

slide-83
SLIDE 83
  • use data from Ge-detectors (same target as CoGeNT)
  • “binned Poisson”

technique sensitivity to νb

[Z. Ahmed et al, 2010]

(more sophisticated ways to treat detectors may lead to stronger limits)

constraints: CDMS-II low thresh.

1 − α = (1 − αbin)Nbin probability to see as few events as observed in one bin

Friday, 16 March, 12

slide-84
SLIDE 84
  • superheated droplets from (total active mass ~0.2kg)
  • light target! use exposure 14.8 kg days (Stage I of Phase II)
  • threshold ~ 8 keV
  • bserved: 9 events; expected (neutron) background ~12
  • include heat transfer and bubble nucleation efficiency
  • we use simple Poisson on Stage I including bkg.

constraints: SIMPLE

C2 Cl F5 [Felizardo et al, 2011]

Friday, 16 March, 12

slide-85
SLIDE 85

constraints from ‘null’ searches

99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10 1 Xenon10 low th. Xenon100 CDMS-II low th. SIMPLE CoGeNT hull DAMA CoGeNT 99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10 1

Friday, 16 March, 12

slide-86
SLIDE 86

arXiv:1109.0702

Results from 730 kg days of the CRESST-II Dark Matter Search

  • G. Angloher1, M. Bauer2, I. Bavykina1, A. Bento1,5, C. Bucci3, C. Ciemniak4, G. Deuter2, F. von Feilitzsch4,
  • D. Hauff1, P. Huff1, C. Isaila4, J. Jochum2, M. Kiefer1, M. Kimmerle2, J.-C. Lanfranchi4, F. Petricca1, S. Pfister4,
  • W. Potzel4, F. Pr¨
  • bst1a, F. Reindl1, S. Roth4, K. Rottler2, C. Sailer2, K. Sch¨

affner1, J. Schmaler1b, S. Scholl2,

  • W. Seidel1, M. v. Sivers4, L. Stodolsky1, C. Strandhagen2, R. Strauß4, A. Tanzke1, I. Usherov2, S. Wawoczny4,
  • M. Willers4, and A. Z¨
  • ller4

arXiv:1109.0702v1 [astro-ph.CO] 4 Sep 2011

Friday, 16 March, 12

slide-87
SLIDE 87

CRESST

  • II, a neutrinob observatory?

W Ca O Neff = 100 ∆m2 = 2.5 × 10−10 eV2 dotted: hep neutrinos solid: 8B neutrinos CaWO4 target Er [keV] dR/dEr (cpd/kg/keV) 20 18 16 14 12 10 8 6 4 2 102 101 1 10−1 10−2 10−3 10−4 10−5 10−6

arXiv:1109.0702

Results from 730 kg days of the CRESST-II Dark Matter Search

  • G. Angloher1, M. Bauer2, I. Bavykina1, A. Bento1,5, C. Bucci3, C. Ciemniak4, G. Deuter2, F. von Feilitzsch4,
  • D. Hauff1, P. Huff1, C. Isaila4, J. Jochum2, M. Kiefer1, M. Kimmerle2, J.-C. Lanfranchi4, F. Petricca1, S. Pfister4,
  • W. Potzel4, F. Pr¨
  • bst1a, F. Reindl1, S. Roth4, K. Rottler2, C. Sailer2, K. Sch¨

affner1, J. Schmaler1b, S. Scholl2,

  • W. Seidel1, M. v. Sivers4, L. Stodolsky1, C. Strandhagen2, R. Strauß4, A. Tanzke1, I. Usherov2, S. Wawoczny4,
  • M. Willers4, and A. Z¨
  • ller4

arXiv:1109.0702v1 [astro-ph.CO] 4 Sep 2011

Friday, 16 March, 12

slide-88
SLIDE 88

CRESST

  • II, a neutrinob observatory?
  • 8 CaWO4 crystals, total of 730 kg days effective exposure
  • measure scintillation light and phonons from nuclear recoil
  • in a nutshell: 67 events in acceptance region; only half of which can

(currently) be attributed to backgrounds. => assess the viability of a signal we have to deal with the backgrounds (at least in some minimal way)

arXiv:1109.0702

Results from 730 kg days of the CRESST-II Dark Matter Search

  • G. Angloher1, M. Bauer2, I. Bavykina1, A. Bento1,5, C. Bucci3, C. Ciemniak4, G. Deuter2, F. von Feilitzsch4,
  • D. Hauff1, P. Huff1, C. Isaila4, J. Jochum2, M. Kiefer1, M. Kimmerle2, J.-C. Lanfranchi4, F. Petricca1, S. Pfister4,
  • W. Potzel4, F. Pr¨
  • bst1a, F. Reindl1, S. Roth4, K. Rottler2, C. Sailer2, K. Sch¨

affner1, J. Schmaler1b, S. Scholl2,

  • W. Seidel1, M. v. Sivers4, L. Stodolsky1, C. Strandhagen2, R. Strauß4, A. Tanzke1, I. Usherov2, S. Wawoczny4,
  • M. Willers4, and A. Z¨
  • ller4

arXiv:1109.0702v1 [astro-ph.CO] 4 Sep 2011

Friday, 16 March, 12

slide-89
SLIDE 89

CRESST

backgrounds

(one of 8 detector modules)

e−/γ

α

206Pb 210Po →206 Pb + α

in or on the surface

  • f the clamps holding

the crystals

n

Friday, 16 March, 12

slide-90
SLIDE 90
  • we follow CRESST in their

modelling of backgrounds

CRESST

fits

=> e/gamma events known => others essentially flat distributed

CRESST-II 730 kg×days Ev (keV) counts/keV 40 35 30 25 20 15 10 10 8 6 4 2

  • bserved

n α Pb e−/γ νb CRESST-II 730 kg×days Ev (keV) counts/keV 40 35 30 25 20 15 10 10 8 6 4 2

Friday, 16 March, 12

slide-91
SLIDE 91
  • we follow CRESST in their

modelling of backgrounds

CRESST

fits

=> e/gamma events known => others essentially flat distributed

  • use Poisson log-Likelihood

to fit νb

χ2

P = 2

X

i

 yi − ni + ni ln ✓ni yi ◆

  • best fit yields

χ2

P /d.o.f. = 27.8/28

(recoil spectrum only)

CRESST-II 730 kg×days Ev (keV) counts/keV 40 35 30 25 20 15 10 10 8 6 4 2

  • bserved

n α Pb e−/γ νb CRESST-II 730 kg×days Ev (keV) counts/keV 40 35 30 25 20 15 10 10 8 6 4 2

Friday, 16 March, 12

slide-92
SLIDE 92

putting it all together

99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10 1 Xenon10 low th. Xenon100 CDMS-II low th. CRESST-II excl. CoGeNT hull DAMA CoGeNT CRESST-II 99% C.L. ∆m2 [eV2] Neff 10−9 10−10 100 10 1

Friday, 16 March, 12

slide-93
SLIDE 93

Kr threshold S2 software 8.4 keV Neff = 100 ∆m2 = 2.5 × 10−10 eV2 hep

8B

XENON100, 100.9 live days S2 (PE) events 700 600 500 400 300 200 10000 1000 100 10 1 0.1

  • utlook
  • -this model is (very) testable--

prediction for Xenon100 low-threshold analysis prediction for COUPP bubble chamber (CF3I)

COUPP, 60 kg×1 year Neff = 60 ∆m2 = 3 × 10−10 eV2 DM hep

8B

Ethr (keV) events 30 25 20 15 10 5 10000 1000 100 10 1 0.1

Friday, 16 March, 12

slide-94
SLIDE 94
  • utlook II
  • elastic scattering off scintillating mineral oil

[Borexino is the best candidate experiment]

neutrino searches?

14C

hep

8B

R14 = 10−23 C9H12 (quenched) energy (keV) events/day/MeV/ton 200 180 160 140 120 100 80 60 40 20 103 102 101 1 10−1 10−2 10−3 10−4 10−5

mainly proton recoils (we used SRIM) however, Borexino has C14 contamination of

10−18

Friday, 16 March, 12

slide-95
SLIDE 95
  • inelastic processes ?

=> excitation in neutrino searches (4.4 MeV gamma) => more generally, look for nuclear excitations e.g. “Kamland-Zen bump”

  • astrophysical consequences

=> stellar cooling constraints => CMB Neff = 4 ? => SN: nearby / dynamics of explosions / sensitivity to tiny mass splittings

  • utlook III

Visible Energy (MeV) 1 2 3 4

1

10 1 10

2

10

3

10

4

10

U Series

238

Th Series

232

Bi

210

Kr

85

External BG Spallation Data Xe 2

136

2nu region 0nu region

  • 238U series
  • 232Th series
  • 40K
  • (134Cs,137Cs)
  • 238U series
  • 232Th series
  • 210Bi
  • 85Kr

From Others

  • Spallation(10C, 11C)

(2.2 < E < 3.0 MeV, R< 1.2m) 2nu

208Tl distributed here.

??

[Azusa GANDO, Moriond 2012]

12C

Friday, 16 March, 12

slide-96
SLIDE 96

conclusions

  • “Old Backgrounds”

=> cosmic ray muon flux unlikely source for the modulation signals in DAMA and CoGeNT => DAMA can do better in convincing us that the above is true

  • “New Signals”

=> periodic signals contain higher harmonics which may provide further discriminating power in telling background from signal => entertained a model of neutrinos which can give similar “DM-like” signals in DM direct detection experiments

Friday, 16 March, 12