Oscar Saavedra

Oscar Saavedra
Torino University, Italy
LAY OUT
• LSD at Mt. Blanc
• On-line Burst detection by LSD at Mt. Blanc
• IMB, K-II and BST SN-neutrino detection time
• Correllations between LSD - K-II and BST
•Conclusions

Liquid Scintillator Detector (LSD)
Istituto di Cosmogeofisica del CNR,
Istituto Di Fisica generale
Universita’ di Torino, Italy
M.Aglietta,
G.Badino,
G.Bologna,
C.Castagnoli,
A.Castellina,
W.Fulgione,
P.Galeotti,
O.Saavedra,
A.G.Trinchero,
S. Vernetto
The Institute for Nuclear Research
of the Accademy of Scienze
of USSR-Moscow
V.L.Dadykin,
F.F.Khalchukov,
P.V.kortchaguin,
V.B. Kortchaguin,
A.S. Malguin,
V.G.Ryassny,
O.G. Ryazhskaya,
V.P.Talochkin,
G.T.Zatsepin
V.F.Yakushev

Liquid Scintillator Detector (LSD)
Fe (10 cm)
Fe (2 cm)
6 m
H=5200 m.w.e. 72 counters 90 tons of С n H 2n (n~9), 200 tons of Fe
8m
General view of LSD
4.5 m

Detection of e + from the reaction
ν ~
that has a large -p cross section.
σ +
~9.3E ⋅10
см
2 44 2
e p −
υ%
e
It was shown for the first time by G.T.Zatsepin, O.G.Ryazhskaya, A.E.Chudakov (1973):
with τ∼180 – 200 µs.
e
General idea
ν ~
е
+
p →e
n+ p→ d+ γ E = 2.2 МэВ
γγ
+
E = 2.
2
+ n
E e + >> 0.5 MeV
MeV

Neutrino ’84, 11th Int. Conf.on Nutrino Physics and Astrophysics

А
How can the neutrino burst be identified ?
T
τ τ
τ=500μs
t
τ
t
The detection of the burst
of N impulses in short
time interval T
∞
∑ ∫
1
N ~ ⋅ I ( E ) ⋅ ( E ) dE ⋅ M
2 ν i ν σ i ν i
4πR
5 MeV
0.8 MeV
ν ~
е
i E thr
+
p
→
e
+
+
n
If R ~ 10 kpc
N int ~ 50 in LSD
Δt ~ 5-20 sec
E e + < 50 MeV

F
imit
=
f
N - 1
Δ t
N > 2
1 ms < Δ t < 600 sec
∞
∑
n=
N−1
P
( n,
Δt)
=
f
F
∞
∑
imit
n=
N−1
e
ON-LINE:
search for cluster of pulses in real-time
− fΔt
( fΔt)
n!
if Fimit
< 1/10 day print-out
Conditions:
Only 1 pulse/N tank
E < 60 MeV
n
Avoid some noise,
uniform distribution,
scape muons, etc
OFF-LINE
< 0.1 %

Phase A
On-line Burst detection by LSD
at Mt. Blanc

February 23, 1987
2 h 52 min.

On line print of five pulses on 23 February 1987 at 3 hr, 52 min, IT
Detected at Mt. Blanc LSD experiment

Number of bursts as
function of their duration
ΔT (sec) for Multiplicities
n ≥ 5, ≥ 10 and ≥ 15
f=0.012 events/sec

Telex from
S. Cristiani from
ESO, Chile
27/02/1987

Circular No. 4332
I. A. U.
2/28/1987

# of
event
1
2
3
4
5
1
2
Time, Time,
UT±2ms UT 2ms
2:52:36,79
40,65
41,01
42,70
43,80
7:36:00,54
7:36:18,88
Energy,
MeV
6,2 – 7
5,8 – 8
7,8 –11 11
7,0 – 7
6,8 – 9
8
9
Events, detected by LSD
February,23, 1987 (SN 1987 A)

Phase B
IMB, K-II and BST SN-neutrino
detection time

Mt. Blanc – LSD events
7 hr 36 min. 005s 9.0 MeV tank 2
7 hr 36 min. 18.9s 6.4 MeV tank 14
Europhys. Lett. 3,1315,1987

All pulses recorded in LSD from 2:37:43 to 3:01:47 UT on Feb.23
Events No. 983, 1003 and 1007 are cosmic ray muons
All pulses recorded in LSD near the Kamiokande-IMB.
Events No. 1281 and 1300 are cosmic ray muons

Scater plot of all events detected
on Feb/23/1987 since 2:00:00 to
8:15:00 UT.
The Y axis is the energy up to 20
MeV. Large vertical arrows show
The arrival time of cosmic muons.
The small arrows, below the time
axes are the authomatic electronic
test.

umber of burst as a function of thei duration for mulipliciyof pulses n=2, n=3 and n=4 (fig. a)
nd for n ≥ 5, n ≥ 10, n ≥ 15 and for n ≥ 20 (fig. b). From 9/28/1986 to 5/23/1987.
T=217.7 days, N = 234.168, = 0.012 ev/sec
≥

for 7

Two bangs can produced
the two separated neutrino burst?
•De Rujula
• Imshennik and Ryazhskaya

View from
aside
ν e
ν ν~
,
The Two-Stage Gravitational Collapse Model
[Imshennik V.S., Space Sci Rev, 74, 325-334 (1995)]
ω r
5 h later
A rotating collapsar
M <
2
υ > υ
2
υ r
M
1
1
υ r
M
2
1
1
M
2
, J υr
1
, J
2
View from
above
The difference of neutrino emission in the standard
model and in the model of rotating collapsar.
Imshennik V.S., Ryazhskaya O.G., 2004

E
E
E
ν e
~ ν
ν
e
e
μ
ν e
~
The difference of neutrino emission in the standard
model and in the model of rotating collapsar.
T c ~5x10 12 K
= 12MeV
= 10MeV
ν ,
~ ν , ν ,
~ ν
μ
τ
τ
=
( 20
−
ν μ
~
25)
ν τ
~
MeV
ρ
~
2.
6
T c ~5x10 10 K
14
⋅10 g ⋅cm
The main reaction:
−
p+ e → n+
ν
E = (30 −55)
MeV
53
52
ε ~ = 5. 3⋅10
erg ε ~ ε = 8. 9⋅10
erg
ν , ν
ντ
V.S.Imshennik, O.G.Ryazhskaya Astro. And Astrophys.
Astro-ph/0401613
ν μ
ν
νe
e
ν , ν
e
e
ν
≈ ν
e
−3
e
ν e
ν e

Phase C
Correllations between LSD - K-II
and BST

LSD Δt = 1.0 ms
Kamioka-LSD correlations
- 60 - 60 s s + + 60 60 s s
Kamioka Δt= 60 sec
0
shift

T: from 1:45 to 3:45
LSD: 91 events, f=0.72/min
E th ≥ 5-7MeV
K-II: 191 events, f=1.4/min
E th ≥ 7.5MeV (20 hits)

2
C
10
8
6
4
LSD-KAMIOKANDE Coincidences
in 34 hours- 17-2 hrs intervals – 11.45-22 Feb. – 21.45 - 23 Feb
1462 events at LSD
2890 events at Kamioka
Δt = 0.5 s
Shift = 7.0 s
Shift = 6.9 s
Expected: 2.03
11.45 17 .45 23.45 5.45 11.45 17.45
2-22 2-23 TIME U.T

91 Mt. Blanc events
240 Baksan events

Annals New YORK Academy of Sciences,
Vol. 571, pag. 577
New York 1989
Edited by Ervin Fenyves

Feb/23/1987 at 7:35 UT
T IMB -T KAM = 7.7 sec
T IMB –T BAK =-30.4 sec

Coincidences between LSD and K2 in the period from 1:45 - 3:45 UT, Feb. 23 1987.
The coincidence window is 0.5 sec.
±
BST

Coincidences between LSD and BST in the period from 1:45 UT to 3:45, Feb. 23 1987.
The meaning of the index is:
K-II

Conclusions
• LSD detected on real time a burst of 5 signals at 2:52:36
before optical observation.
Means this signal the first bang of the SN1987a?
Can two bangs or rotated SN star model explain this effect?
•LSD detected one pulse at the IMB-K-II time
• A series of coincidences have been found among
LSD-Kamiokande-Baksan underground detectors in a period
encompassing 1.5-2.0 hrs the Mt. Blanc burst.
Are the LSD, Kamioka, Baksan pulses real one?
The “phantastic effect”, as is called by Chudakov, are
something to do with the SN1987a?
If it is so, what they are?