Transcript On PRISMA project (proposal)

On PRISMA project (proposal)
Yuri V. Stenkin
INR RAS
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The Project aims
Why PRISMA?
 PRImary Spectrum Measurement Array
 The main aim is: TO SOLVE THE “KNEE
PROBLEM”
 Other aims:

– cosmic rays spectra and mass composition
– cosmic ray sources
– applied Geophysical measurements
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History & Motivation
Why we need a new project?
1. The “knee problem” is a milestone of cosmic ray physics.
2. Very few experiments have been designed specially for that and
KASCADE (KArlsruhe Shower Core and Array DEtector) is the best
one.
3. The problem still exists.
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EAS
method
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1. The “knee problem”
The problem is exactly 50-years old!
In 1958 there was published a paper (G.V. Kulikov & G.B. Khristiansen)
claiming the knee existence in cosmic ray energy spectrum.
They observed a sharp change of slope in EAS size spectrum and
proposed a model describing this effect as an evidence of existence of 2
sources of c. r.: Galactic and Metagalactic ones.
But, from the beginning and up to now there exist alternative
explanations of this effect (S.I.Nikolsky, Kazanas & Nikolaidis,
A.A.Petrukhin, Yu.V. Stenkin).
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Examples of alternative explanations
N
Petrukhin
New processes
knee

"излом"
knee
Stenkin
EAS
method
systematic

EAS
энергия
energy
ШАЛ
E0 E2
Primary
первичная
energy
энергия
E1
недостающая
Missing
energy
энергия
E
Primary
energy
Missing energy
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Primary
energy
E
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EAS components equilibrium
No of particles
Break of equilibrium
Break in attenuation
Depth in atmosphere
“knee”
in Ne spectrum
From Hayakawa manual on cosmic ray physics
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When the break occurs?
At E~100 TeV / nucleon
 For p: 100 TeV
 For Fe: 5 PeV (just the knee region)

This figures are sequences of : Lint= 90 g/cm2 in air
the Earth’s atmosphere thickness =1030 g/ cm2 (depending on altitude)
For details see: Yu.Stenkin, Yadernaya Phys., 71 (2008), 99
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2. Existing experiments

KASCADE
It gave many interesting results.
BUT, it did not answer the question on the
knee origin and thus,
It has not solved the knee problem!
Moreover, the problem became even less
clear….(see G. Schatz. Proc. 28th ICRC, Tsukuba, (2003), 97
or Yu. Stenkin. Proc. 29th ICRC, Pune (2005), v.6, 621)
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KASCADE -> KASCADE-Grande
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KASCADE hadronic calorimeter
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KASCADE group connected visible knee in PeV region with c. r.
protons.
Tibet AS experiment results contradict this hypothesis:
they connect the knee with iron primary.
In this case there should be the iron knee at E~1017 eV.
- Nobody saw this.
C. R. should consist only of heavy nuclei at E>07 eV or one
has to adjust many parameters to make full compensation.
- Nobody saw this. It contradicts emulsion chamber
experiments (Pamir) and air luminescence data (Hi Res).
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Compilation of experimental data (astro-ph/0507018)
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KASCADE EAS h-size spectra
“knee”???
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A. Haungs, J. Kempa et al. (KASCADE) Report FZKA6105 (1998);
Nucl. Phys. B (Proc. Suppl.) 75A (1999), 248
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KASCADE is very precise classical instrument for EAS study.
It would be difficult and useless to try to make better array.
On my opinion the only way is:
to make a device based on new
principles (asymmetrical answer)
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PRISMA would be the answer.
Prism
PRISMA
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New principles
The main EAS component is: hadrons
Therefore, let us concentrate mostly on the hadronic component
Bun, instead of huge and expensive hadron calorimeter of fixed area,
let us make simple, inexpensive and of unlimited area detector.
How this could be done?
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New Methods
2 new methods have been developed in our Lab.
1st method is based on thermal neutrons “vapour” accompanying EAS
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en-detector design
PMT
plastic
housing
6Li(n,a)3H+4.8
MeV
Scintillator: ZnS(Ag)+6LiF
ZnS(Ag) is a unique scintillator for heavy particles
detection:
Similar to that using in neutron
imaging technique
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160,000 photons per capture
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The detector is almost insensitive to single charged particles.
But, it can measure the number N of charged particles if N>5.
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Thermal neutron time distributions
Multicom Prototype, Baksan
Prisma prototype, Moscow
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Another advantage of this detector is a possibility to
measure thermal neutron flux of low intensity and its
variations
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2d new method:
The Muon Detector as a 1-layer hadronic calorimeter:
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This picture represents a density map as measured by Carpet (left, shown in LOG
scale) and by MD (right, linear scale in relativistic particles). (Detector in the center
show a particle density of ρc=8*1.1252/0.5=5800 m-2.
jet of (26+17)/2=21.5 particles per m2 in MD. Jet size is very narrow (~1 m) with
normal rather low density around it and second: the distance from the EAS core is large
enough and equal to 48 m.
r core= 5800 / m2
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r jet = .5 /m2
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Preliminary Baksan data: hadrons at R=47m
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Muon/hadron ratio distribution
Preliminary data
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Carpet: 400*1m2 en-detectors
grid with spacing of 5 m
Central muon detector:
400*1m2 plastic scinillators
Muon detector tunnels:
1200*1m2 plastic scintillators
Outer trigger detectors:
4*25*1m2 plastic scintillators
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M-C simulations. CORSIKA 6.501 (HDPM, Gheisha6)
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M-C simulations. CORSIKA 6.501 (HDPM, Gheisha6)+array
neutrons:
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407158 Nmu=
794 E0/1TeV=
355.0245
-4.448307 y0= -27.31079
TETA=
13.80
FI=
3094504.
Part_type=
5626
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A map
of an event
in neutrons
161.49
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M-C
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Main features:
•Range in primary energy:
from ~10 TeV to ~30 PeV
•energy resolution:
~ 10%
•angular resolution:
~ 1o
•core location:
< 2.5 m
•capability to measure independently: Ne, Nh, Nm
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Location
It depends on:

Collaboration Institutions
 budget
 altitude (high altitude is preferable)
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Involved Institutions:
1. Institute for Nuclear Research, Moscow
2. MEPhI, Moscow
3. Skobeltsyn Institute, MSU, Moscow
4.
5.
To be continued...
The collaboration is open for other participants.
You are welcome!
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Thank you!
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