On PRISMA project (proposal)

Yu. Stenkin, UHECR'2008 1

On PRISMA project (proposal)On PRISMA project (proposal)

Yuri V. Stenkin

INR RAS


The Project aimsThe Project aims

Why PRISMA?PRImary Spectrum Measurement ArrayThe main aim is: TO SOLVE THE “KNEE

PROBLEM”Other aims:

– cosmic rays spectra and mass composition– cosmic ray sources– applied Geophysical measurements


History & MotivationHistory & 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 andKASCADE (KArlsruhe Shower Core and Array DEtector) is the best one. 3. The problem still exists.


EASmethod


1. The “knee problem”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).


Examples of alternative explanationsExamples of alternative explanations

энергияШ АЛ

первичнаяэнергия

E 2 E 1недост ающ ая

энергия

E

"и злом "

N

E 0E

Petrukhin StenkinNew processes

knee

Primaryenergy

EASenergy

Missing energy Missing energyPrimaryenergy

Primaryenergy

kneeEASmethodsystematic


Depth in atmosphere

No of particles

From Hayakawa manual on cosmic ray physics

EAS components equilibrium

Break of equilibrium

Break in attenuation

“knee” in Ne spectrum


When the break occurs?When the break occurs?

At E~100 TeV / nucleonFor p: 100 TeVFor Fe: 5 PeV (just the knee region)

For details see: Yu.Stenkin, Yadernaya Phys., 71 (2008), 99

This figures are sequences of : Lint= 90 g/cm2 in airthe Earth’s atmosphere thickness =1030 g/ cm2 (depending on altitude)


2. Existing experiments2. 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)


KASCADE -> KASCADE-GrandeKASCADE -> KASCADE-Grande


KASCADE hadronic calorimeter


KASCADE group connected visible knee in PeV region with c. r. protons.

- Nobody saw this.

C. R. should consist only of heavy nuclei at 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).

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.


Compilation of experimental data (astro-ph/0507018)


KASCADE EAS h-size spectraKASCADE EAS h-size spectra

“knee”???


A. Haungs, J. Kempa et al. (KASCADE) Report FZKA6105 (1998); Nucl. Phys. B (Proc. Suppl.) 75A (1999), 248


to make a device based on new to make a device based on new principles (asymmetrical answer)principles (asymmetrical answer)

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:


PRISMA would be the answer.PRISMA would be the answer.

PRISMAPrism


New principlesNew 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?


New MethodsNew Methods

2 new methods have been developed in our Lab.

1st method is based on thermal neutrons “vapour” accompanying EAS


en-detector designen-detector designPMT

housing

6Li(n,a)3H+4.8 MeV

160,000 photons per capture

ZnS(Ag) is a unique scin-tillator for heavy particlesdetection:

plastic

Scintillator: ZnS(Ag)+6LiF

Similar to that using in neutronimaging technique


The detector is almost insensitive to single charged particles.But, it can measure the number N of charged particles if N>5.


Thermal neutron time distributionsThermal neutron time distributionsMulticom Prototype, Baksan Prisma prototype, Moscow


Another advantage of this detector is a possibility to Another advantage of this detector is a possibility to measure thermal neutron flux of low intensity and its measure thermal neutron flux of low intensity and its variationsvariations


2d new method:2d new method:The Muon Detector as a 1-layer hadronic calorimeter:The Muon Detector as a 1-layer hadronic calorimeter:

Yu. Stenkin, UHECR'2008 26corem2

jet m2This picture represents a density map as measured by Carpet (left, shown in LOG 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 scale) and by MD (right, linear scale in relativistic particles). (Detector in the center show a particle density of show a particle density of ρρc=8*1.1252/0.5=5800 mc=8*1.1252/0.5=5800 m-2-2. . jet of (26+17)/2=21.5 particles per mjet of (26+17)/2=21.5 particles per m22 in MD. Jet size is very narrow (~1 m) with 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 normal rather low density around it and second: the distance from the EAS core is large enough and equal to 48 m.large enough and equal to 48 m.


Preliminary Baksan data: hadrons at R=47m


Preliminary data

Muon/hadron ratio distribution


Carpet: 400*1m2 en-detectorsgrid 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


M-C simulations. CORSIKA 6.501 (HDPM, Gheisha6)


neutrons: . . . . . . . . . . . . . . . . . . 12 . . . . . 4 . . . . . . . . . . . . . . . . . . . * . . . . . . . . . . . . . . . . . 5 * 21 . . . . . . . . . . . . . . . . . . . . . . . . 4 . . 4 . . . * . . . . . . . . . . . 8 * . . . 4 . 17 7 . . . . . . . . . . . . . . . * . . . . . . . . . . . 10 . . . . . . . . . . . . . . . . . . . . . . 25 . 36 12 . . . 5 . . . . . . . . 7 . . . . 9 5 . . . . . * 14 . . . . . . . . . 5 8 22 * 4 . . . . . . . . . . . . . * 11 17 11 * . . 12 . . . . . . . 16 . . . * . . . 16 * . . . . 4 * . . . . . . . . 19 8 9 12 35 13 13 5 7 . 7 . . . * 14 . 9 . . . . . 13 12 24 25 . 23 11 . . . . . . . . 4 . . . . 17 15 22 29 27 19 4 10 * . . . . . 13 . . 7 15 . . 23 11 25 11 7 . 16 14 . . * . . . . 5 . . . 9 . 13 20 . 5 * . 5 7 . . . . . . . . 4 . . 4 . 10 10 19 . . . . . . . . . . . . 11 . . . 12 . . 7 . . . . . . 18 .

Ne= 407158 Nmu= 794 E0/1TeV= 355.0245 x0= -4.448307 y0= -27.31079 TETA= 13.80 FI= 161.49 Z= 3094504. Part_type= 5626

M-C simulations. CORSIKA 6.501 (HDPM, Gheisha6)+array

A mapof an eventin neutrons


M-C


Main features: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, N


LocationLocation

Collaboration Institutions budget altitude (high altitude is preferable)

It depends on:


Involved Institutions:Involved Institutions:

1. Institute for Nuclear Research, Moscow2. MEPhI, Moscow3. Skobeltsyn Institute, MSU, Moscow4.5.

To be continued...

The collaboration is open for other participants.

You are welcome!


Thank you!Thank you!

On PRISMA project (proposal)

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