Ten years of cosmic muons observation with Borexino Davide DAngelo - - PowerPoint PPT Presentation
16 th International Conference on Topics in Astroparticle and Underground Physics 9-13 September 2019 Toyama, Japan Ten years of cosmic muons observation with Borexino Davide DAngelo on behalf of the Borexino Collaboration Universit
Davide D’Angelo
Università degli Studi di Milano Istituto Nazionale di Fisica Nucleare, sez. di Milano
16th International Conference on Topics in Astroparticle and Underground Physics 9-13 September 2019 Toyama, Japan
2 TAUP 2019 – Borexino Cosmic Muons
Ø A low energy neutrino detector Ø based on elastic scattering on electrons Ø highly purified organic liquid scintillator Solar neutrinos: 7Be, 8B, pep, pp and possibly CNO. Geo-neutrinos, supernova explosion, neutrino magnetic moment, … See talk by S. Zavatarelli See talk by L. Ludhova
3
Water Tank: γ and n shield μ water Č detector 208 PMTs in water 2100 m3 Scintillator: 278 t PC+PPO (1.4 g/l) Stainless Steel Sphere:
(light quenched) Nylon vessels: (125 μm thick) Inner r: 4.25 m Outer r: 5.50 m (radon barrier)
TAUP 2019 – Borexino Cosmic Muons
3800m w.e. of rock shielding
Spherical detector: no systematics due to angular dependence of the acceptance
TAUP 2019 – Borexino Cosmic Muons 4
Ø A low energy neutrino detector Ø based on elastic scattering on electrons Ø highly purified organic liquid scintillator Solar neutrinos: 7Be, 8B, pep, pp and possibly CNO. Geo-neutrinos, supernova explosion, neutrino magnetic moment, …
Ø Also a powerful detector for muons, neutrons and
cosmogenic backgrounds.
Ø Muon detection occurs with both Inner and Outer
detector
Phase 2
chain solar neutrinos: Nature 562, 505–510 (2018)
May 2007 May 2010 Oct. 2011 Purification
Preparation
5
TAUP 2019 – Borexino Cosmic Muons
Jan 2017
Phase 1
precision; Day/Night asymm.;
6 cycles of water extr. temperature stabilization
CNO Campaign
Phase 2
chain solar neutrinos: Nature 562, 505–510 (2018)
May 2007 May 2010 Oct. 2011 Purification
Preparation
6
TAUP 2019 – Borexino Cosmic Muons
Jan 2017
Phase 1
precision; Day/Night asymm.;
6 cycles of water extr. temperature stabilization
CNO Campaign 10 years observation of cosmogenic muons!
7 TAUP 2019 – Borexino Cosmic Muons
An IOP and SISSA journal
The Borexino collaboration
16th May 2007 – 15th May 2017 CNGS muons (2008-2012) removed 3218 days used no prolonged downtimes Muons crossing both Inner and Outer Detector
Detector cross sections for muons:146 m2 Total exposure: 4.2 105 m2 d
TAUP 2019 – Borexino Cosmic Muons
8
]
Average Muon Flux [d
4100 4200 4300 4400 4500 4600
Borexino Muon Data Seasonal Modulation Fit
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
σ (Data-Fit)/
6 − 4 − 2 − 2 4 6
Iµ(t) = I0
µ + δIµ cos
✓2π T (t − t0) ◆
± · is δIµ = (58.9±1.9) d−1 = (1.36±0.04)% ± Jun 25th
x I0
µ = (3.432±0.001)·10−4 m−2s−1
±
−1
is χ2/NDF = 3921/3214.
Period fixed to
Rate and
Better
9 TAUP 2019 – Borexino Cosmic Muons
Jan Mar May Jul Sep Nov ]
Average Muon Flux [d
4200 4250 4300 4350 4400 4450
10 yr Borexino Data Seasonal Modulation Fit
is χ2/NDF = 13702/362.
Muons originate from π and K
meson decay high in the atmosphere.
The muon flux observed
underground depends on the fraction of mesons that decay before first interaction
Hotter air is less dense leading
to reduced interaction chance
10 TAUP 2019 – Borexino Cosmic Muons
T [K] 200 210 220 230 240 250 260 270 280 290 300 1 10
2
10
3
10 Height [km] 10 20 30 40 50 60 Normalized Weight 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Pressure [hPa]
Normalized Weights Temperature Normalized Weights (!
n $ + ! n K)
TAUP 2019 – Borexino Cosmic Muons
11
∆Iµ I0
µ
= ⇤ ∞ dXα(X)∆T(X) T 0(X) Teff ⇤ N
n=0 ∆XnT(Xn)(W π n + W K n )
N
n=0 ∆Xn(W π n + W K n )
W π,K(X) ⇤ (1 X/Λ⇥
π,K)2eX/Λπ,KA1 π,K
⇥ + (⇥ + 1)B1
π,KK(X)(⌅Eth cos ⌅⇧/⇤π,K)2
∆Iµ I0
µ
= T ∆Teff Teff T(X) W(X)
h i , hEthr cos ✓i = (1.34 ± 0.18) TeV
new from our simulation [formerly 1.833 TeV from Grashorn et al. (2010)]
d A1
K = 0.38 · rK/π, w
eter B1 considers
TAUP 2019 – Borexino Cosmic Muons
12 Time
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
Temperature [K]
212 214 216 218 220 222 224 226 228 230
ECMWF Data Seasonal Modulation Fit Jul/2014 Dec/2014 Jul/2015 Jan/2016
Deviation from mean (%)
10 − 8 − 6 − 4 − 2 − 2 4 6 8 10
Close agreement also on short scale variations
ü 4 daily measures: 0h, 6h, 12h, 18h. ü 37 pressure levels: [1-1000]hPa. ü 1.5km spaced grid ü interpolate to LNGS coordinates
Sudden Stratospheric Warming (SSW): ~1-2w winter maxima due to artic cyclone deformations. [Geophys. Res. Lett. 36 L05809 (2009)]
Temperature Borexino muon rate European Centre for Medium-range Weather Forecast (ECMWF):
TAUP 2019 – Borexino Cosmic Muons
13
Error halved ! ∆Iµ I0
µ
= T ∆Teff Teff
(%) 〉
eff
T 〈 /
eff
T Δ
5 − 4 − 3 − 2 − 1 − 1 2 3
(%) 〉
µ
I 〈 /
µ
I Δ
10 − 5 − 5 10
Data 0.02 ± = 0.90
T
α
R-value=0.55
Experiment Time period ↵T Borexino (This work) 2007–2017 0.90 ± 0.02 Borexino Phase I [6] 2007–2011 0.93 ± 0.04 GERDA [7] 2010–2013 0.96 ± 0.05 0.91 ± 0.05 MACRO [31] 1991–1997 0.91 ± 0.07 LVD [5] 1992–2016 0.93 ± 0.02
↵T = 1 Dπ 1/✏K + AK(Dπ/DK)2/✏π 1/✏K + AK(Dπ/DK)/✏π ,
↵T = T I0
µ
@Iµ @T
Dπ,K ⌘
✏π,K 1.1hEthr cos ✓i + 1
with some parametrization….
d AK = 0.38⇥rK/π the product of the t
Revising the value from 1.833 TeV to 1.34 TeV, the prediction shifts from αT = 0.92 ± 0.02 to αT = 0.895 ± 0.15
Predicted αT at LNGS:
[TeV] 〉 θ cos
thr
E 〈
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
T
α
0.2 0.4 0.6 0.8 1 1.2 1.4
LNGS Weighted Mean Ice Cube MINOS Double Chooz ND Double Chooz FD Daya Bay EH1 Daya Bay EH2 Daya Bay EH3 Barrett AMANDA
T
α
π
)
T
α (
K
)
T
α ( 0.02 ± = 0.08
π K/
Fit: r
T
α
π
)
T
α (
K
)
T
α ( 0.02 ± = 0.08
π K/
Fit: r
0.85 0.9 0.95 1
Borexino Borexino LVD GERDA I GERDA II MACRO (This Work) (2012)
TAUP 2019 – Borexino Cosmic Muons
14
based on rK/π = 0.149 ± 0.06 literature value
TAUP 2019 – Borexino Cosmic Muons
15
π K/
Atmospheric Kaon to Pion Ratio r 0.05 0.1 0.15 0.2 0.25 0.3
T
α
0.84 0.86 0.88 0.9 0.92 0.94 0.96 0.98
T
α Experimental
T
α Theoretical Fit
2
χ Combined
+0.11
= 0.11
π K/
Best Fit Value: r
[GeV] s
2
10
3
10
π K/
r
0.05 0.1 0.15 0.2 0.25
)
atm
Borexino (this work) (p+A )
atm
MINOS (p+A )
atm
IceCube (p+A NA49 (Pb+Pb) )
/
+p) p E735 (
comparison with existing measurements
−0.07.
gy ps = (190 ± 28) GeV,
√s computed assuming a fixed nucleon target hit by a proton of 18 TeV, computed as 10x the simulated
gy hEthri = (1.8±0.2) TeV , given that cosmic muons
TAUP 2019 – Borexino Cosmic Muons
16
]
Average Muon Flux [d 4300 4310 4320 4330 4340 4350 4360 2007 2008 2015 2009 2010 2011 2012 2013 2014 2016 2017
Borexino Muon Data Long-Term Modulation
Ampl = (0.34±0.04)% Tlong=(8.25+0.82)yr muon flux
not in T!
ü we speculate on a possible correlation ü we cannot prove nor rule out a correlation ü anti-correlation observed in this work, dominated by MACRO+LVD data:
ü
puzzle, JCAP 07 (2012) 029
Period [d] 10
2
10
3
10
4
10 Lomb-Scargle Power P
1 −
10 1 10
2
10
3
10 99.5% C.L. Sunspot Data
TAUP 2019 – Borexino Cosmic Muons
17
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
Sunspot Number
20 40 60 80 100 120 140 160 180 200 220 240 Sunspot Data Solar Cycle Fit
F(t) = A ✓t − ts b ◆3 " exp ✓t − ts b ◆2 − c #−1
Half Period/ Rise Time [d] Maximum Muon Flux (Sinusoidal Fit) 1505 ± 150 16th of June 2012 ± 271 d Muon Flux (Gaussian Fit) 1207 ± 116 4th of March 2012 ± 180 d Solar Sunspot Activity (Gaussian Fit) 1578 ± 3 8th of April 2013 ± 5 d
Jan Mar May Jul Sep Nov ]
Neutrons [d
58 59 60 61 62 63 64 65 10 yr Borexino Data Seasonal Modulation Fit
Jan Mar May Jul Sep Nov ]
Neutron-producing muons [d
35.5 36 36.5 37 37.5 38 38.5 10 yr Borexino Data Seasonal Modulation Fit
TAUP 2019 – Borexino Cosmic Muons
18
n-producing muons low (<10) multiplicity neutrons
ü We observe neutron capture gammas (2.2 or 4.9 MeV) in the wake (τ~ 260μs) of muons. ü Modulation in the neutron rate only with a low multiplicity cut (<10). ü Showering muons with neutron multiplicity up to 1000 neutrons
ü Confirmed by Lomb-Scargle ü Why such high amplitude? Variations in <Eμ>? ü Requires <Eμ> = (280±4.5) GeV. From our simulations it would reflect in >10% muon flux variation which is not
Neutron Phase Amplitude Multiplicity Projected [months] Projected [%] Neutron-producing muons 6.3 ± 0.4 2.3 ± 0.5 n = 1 6.6 ± 0.5 2.3 ± 0.6
We have analyzed 10 years of cosmogenic muons collected with Borexino continuously running.
We reported a high-statistics seasonal modulation with t0=(181.7±0.4) or Jul 1st.
We observed the same modulation in atmospheric temperature data.
We measured the correlation coefficient αT=0.90±0.02
We measured the Kaon/Pion ratio in muon production rK/π=0.11+0.11
We observe a secondary long term modulation with T~8.25yr and main peak in Jun 2012.
We observe seasonal modulation on the cosmogenic neutron rate only for low multiplicity events (<10) and with an amplitude unexpectedly larger than muon modulation.
19 TAUP 2019 – Borexino Cosmic Muons
Tiank you for your atuentjon!
20 TAUP 2019 – Borexino Cosmic Muons
Simone Marcocci 1989-2019
TAUP 2019 – Borexino Cosmic Muons
21
22
TAUP 2019 – Borexino Cosmic Muons
Muon modulation is known since ‘50s:
First observed at LNGS by MACRO in ‘97:
by macro. Astropart. Phys., 7:109–124, 1997.
Extensive by MINOS:
. Adamson et al. (MINOS coll.). Observation of muon intensity variations by season with the MINOS far detector. Phys. Rev. D81, 012001, 2010. arXiv: 0909.4012 [hep-ex]. Also observed at LNGS by LVD and GERDA: M.Selvi (for the LVD coll.) In Proc. 31st ICRC, 2009. C. Vigorito (for the LVD coll.) In Proc. 35th ICRC, 2017. GERDA coll., Astrop. Physics 84 (2016) 29. Borexino previous work Borexino collaboration, Cosmic-muon flux and annual modulation in Borexino at 3800 m water-equivalent depth, JCAP 05 (2012) 015
23 TAUP 2019 – Borexino Cosmic Muons
Abruzzo, Italy 120 Km from Rome
Borexino Detector and Plants
External Labs
24 TAUP 2019 – Borexino Cosmic Muons
f
r
l n t: , e
1 10 Pee 0.2 0.3 0.4 0.5 0.6 0.7 0.8 pp
7Be
pep
8B
Vacuum-LMA MSW-LMA
*oscillation parameters from: I.Esteban, MC.Gonzalez-
Concha, M.Maltoni, I.Martinez-Soler and T.Schwetz, Journal
TAUP 2019 – Borexino Cosmic Muons
25
Borexino only
The whole pp-chain is measured by the same experiment!
TAUP 2019 – Borexino Cosmic Muons
26 Experiment Borexino Borexino I GERDA MACRO LVD I LVD II (This Work) [6] [7] [31] [4] [5] Location Hall C Hall C Hall A Hall B Hall A Hall A Time 2007–2017 2007–2011 2010–2013 1991–1997 2001–2008 1992–2016 Rate [10−4m−2s−1] 3.432 ± 0.001 3.41 ± 0.01 3.47 ± 0.07 3.22 ± 0.08 3.31 ± 0.03 3.3332 ± 0.0005 Amplitude [10−6m−2s−1] 4.7 ± 0.2 4.4 ± 0.2 4.72 ± 0.33 — 5.0 ± 0.2 5.2 ± 0.3 Amplitude (%) 1.36 ± 0.04 1.29 ± 0.07 1.36 ± 0.07 — 1.51 ± 0.03 1.56 ± 0.01 Period [d] 366.3 ± 0.6 366 ± 3 — — 367 ± 15 365.1 ± 0.2 Phase [d] 181.7 ± 0.4 179 ± 3 191 ± 4 — 185 ± 15 187 ± 3