VLOGA ZA (SO)FINANCIRANJE
RAZISKOVALNEGA PROJEKTA ZA LETO 2001
(RESEARCH PROPOSAL)
II. VSEBINA PREDLAGANEGA RAZISKOVALNEGA PROJEKTA
1. Naslov
raziskovalnega projekta (Title of Proposed Project):
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Counter of Cherenkov photons with aerogel radiator
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2. Predlog
projekta (Proposed Research)
2.1.
Izhodišče raziskave in predstavitev problema
(Scientific Background of the Proposed Research):
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Cherenkov radiation caused by fast charged particles in
a transparent medium is the basis for different methods of particle
identification. Up to the present, gaseous and solid (or liquid) radiators
have been used as sources of Cherenkov radiation. The threshold for photon
emission of pions is above 2.5 GeV/c in gases and below 0.2 GeV/c in solids
(or liquids). The intermediate uncovered gap is essential for the
investigation of rare B meson decays, which are the research subject of many
experiments, some in progress, others
in preparation.
A solution to the problem is
offered by silica aerogels, a porous material with refractive index between 1.005
and 1.06. The use of aerogels as Cherenkov radiators has been limited up to
now mainly by its low transparency for light and the fact that aerogels are
hygroscopic. New methods of sythesis and improved manufacturing procedures
have made available aerogels with better
transparency and some are
even hydrophobic. This allows the use of aerogel Cherenkov radiation in
developing detection methods for identifying and separating different species
of particles.
Aerogel has been used as a
Cherenkov radiator in two experiments: the HERMES experiment at the DESY
laboratory in Hamburg, Germany and the BELLE experiment at the KEK institute
in Tsukuba, Japan. The results indicate that it would be meaningful to use
such a radiator also in Cherenkov detectors with thin radiators without
focusing systems of mirrors (so called proximity focusing RICH).The advantage
of such detectors is their compactness, which is especially important for
experiments at the high energy colliders. By making use of improved aerogels,
recently developed multianode photomultiplier tubes and additional lens
systems for elimination of the inefficiency due to the PMT inactive surface,
we propose to develop a method for detection of Cherenkov photons.
The proposed project includes
the construction of an apparatus for testing the performance of a Cherenkov
detector with thin aerogel radiators, without mirror focusing. We shall
investigate and test light collection systems, which are essential since the
PMT active surface is smaller than their full geometrical surface.
A possible application of the
Cherenkov photon detector could be for detection of beta particles. Of
special interest is the detection of the radioactive isotope Sr-90 in the
environment. The isotope Sr-90 is highly radiotoxic due to the fact that it
is a bone seeking element like calcium and that its half-life is 28.5 years.
In addition, the daughter isotope Y-90 emits beta electrons of relatively
high end-point energy (Emax = 2.27MeV). Sr-90 is a fission product, thus it
may pollute the environment following an accident in a nuclear power plant.
In such a case it would be important to quickly and accurately measure its
concentration in various samples. Sr-90 and Y-90 are pure beta emitters, such
that they are not accessible to identification by standard methods of gamma
ray spectrometry. Beta spectrometry, on the other hand, is made difficult by
the fact that the spectrum is continuous with many overlapping contributions
of other radionuclides in the sample. The usual procedure is a multistep
chemical analysis, which is complex and time consuming.
Some time ago, a method has
been proposed by researchers at the J. Stefan Institute, which is based on
the fact that the Y-90 beta spectrum end-point energy is relatively high. A
choice of aerogel with suitable refractive index allows one to select the
threshold energy of beta electrons, which would radiate Cherenkov photons,
e.g. the threshold energy for an aerogel with the refractive index n=1.06 is at 1 MeV. Thus one may separate the
contributions of different
radioactive isotopes.
By modelling the physical
processes produced by beta electrons and the gamma and cosmic ray
backgrounds, we intend to optimize the detector parameters. Such a detector
would allow quick measurements of low activities of the isotope Sr-90 in
environmental samples.
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2.2. Analiza
in pregled relevantne literature (in rezultatov raziskav)
(Present State-of-the-Art in the
Proposed Field of Research):
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The BELLE experiment is the first experiment in
elementary particle physics to use aerogel as a radiator in the threshold
Cherenkov counter, while Cherenkov rings were first observed in the HERMES
experiment (references 1 and 2). The idea of using aerogels in proximity
focusing RICH detectors was presented by T.Iijima (reference 3).
Our experiencies with
multi-anode photomultipliers as single photon detectors (references 5-8) and optical systems for light collection
(reference 9) indicate the possibillity for a development of a photon
detector suitable for proximity focusing RICH counters. Significant progress
in manufacturing procedures of aerogel materials has a large impact on the
proposed project (references 2 and 10-12). For studies of Cherenkov photon
counters with aerogel radiator for measurements of beta activities in
environmental samples, the past experiencies are of special importance. These
were gained at our institute by testing aerogel based detectors with samples
of pure beta emitters (reference 13).
Several authors have already
studied the possibility of Sr-90/Y-90 concentration measurements in water
solutions by using comercial liquid scintillators (references 14-17).
Cherenkov radiation threshold and strong energy dependence of detection
efficiency in water solutions could in principle be used for separation of
radioactive isotopes and for the reduction of low energy beta and gamma
background radiation (reference 18). However, since relatively large
refractive index of water (n=1.33) corresponds to relatively low energy
threshold of 0.263 MeV, most of the
radionuclides in such detector would contribute to a measured signal. For
this reason we estimate the proposed project to have significant benefits.
Reference:
1. T. Iijima et al., Nucl. Instr. and Meth. A453
(2000) 217-221.
2. E. Aschenauer et al., Nucl. Instr. and Meth.
A440 (2000) 338-347.
3. T. Iijima, "Aerogel
Cherenkov Counter in Imaging Mode", JPS Meeting, Tokio, September 1997.
4. I. Adam, "DIRC, the particle
identification system for BABAR", SLAC-PUB-8590, Aug. 2000.
5. P. Križan et al., Nucl. Instr. and Meth. A394
(1997) 27-34.
6. S.Korpar et al., Nucl. Instr. and Meth. A442
(2000) 316-321.
7. S.Korpar et al., Nucl. Instr. and Meth. A433
(1999) 128-135.
8. I.Arinyo et al., Nucl. Instr. And Meth. A453
(2000) 289-295.
9. D.R. Broemmelsiek, Nucl. Instr. and Meth. A433
(1999) 136-142.
10. R. De Leo et al., Nucl. Instr. and Meth. A457
(2001) 52-63.
11. A.R.Buzykaev et al., Nucl. Instr. and Meth.
A433 (1999) 396-400.
12. T. Sumiyoshi et al., Nucl. Instr. and Meth.
A433 (1999) 385-391.
13. D.Brajnik et al., Nucl. Instr. and Meth. in
Phys. Res. A353 (1994) 217-221.
14. W.J. Gelsema et al., Int. J. Appl. Radiat.
Isot. 26 (1975) 443.
15. J.E. Martin, Int. J. Appl. Radiat. Isot. 38
(1987) 953.
16. H.H. Ross, Anal. Chem. 41 (1969) 1260.
17. B. Carmon, Int. J. Appl. Radiat. Isot. 30
(1979) 97.
18. K.Walter
et al., Radio. Acta 62 (1993) 207-212.
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2.3. Pomembnost
pričakovanih raziskovalnih rezultatov (Scientific/Technological
Relevance):
2.3.1. Pomen
za razvoj znanosti (Relevance to Science Development):
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Identification of charged elementary particles, in
particular the separation between
kaons and pions, is essential in experimental studies of rare decays of B and D mesons. By using silica aerogel
as radiator medium in proximity focussing RICH counters it will be possible
to further develop identification methods, which will be of prime importance
for CP violation measurements in two body decays of B mesons.
The project is important also
for a further development of a method for radioactivity measurements of pure
beta emitters by using Cherenkov radiation in aerogel. It is expected that by
optimizing individual components of the system the efficiency for detection
of beta electrons from the Sr-90 decay chain will be high enough to allow for
quick and simple low concentration measurements of this highly radiotoxic
isotope.
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2.3.2. Pomen
za aplikacijo (Relevance to Application):
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An apparatus for low level radioactivity measurements of Sr-90, which could be
designed as a result of the proposed project, could allow for easy handling
and quick response in quality assessment of food.
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2.3.3. Pomen za sofinancerje/uporabnike
(Relevance to Beneficiaries):
2.3.4. Pomen
za širjenje in izkoriščanje znanja (za aplikativne raziskave)
(Dissemination and Exploitation of Results):
2.4. Podroben
opis programa raziskovalnega projekta
(Detailed Description of the Work Programme):
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-setting up of a system with an aerogel based proximity
focussing RICH counter by using the available equipment
-study of light collection
systems for Cherenkov photons
-system test with cosmic rays
-upgrade of the system,
on-the-bench and beam tests
-setting up of a system for
low level radioactivity measurements
of Sr-90
-optimisation of the low level radioactivity apparatus by
modelling the relevant phyical
processes, testing
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2.5. Časovna
razporeditev (Timescale):
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First year: setting up of a proximity focussing RICH counter by using the
available equipment.
Second year: upgrade of the
counter, test beam and cosmic ray tests, setting up of a detection system for
beta emitters.
Third year: finalize the low level beta radioactivity apparatus.
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2.6. Raziskovalna oprema (Research Equipment):
2.6.1. Razpoložljiva raziskovalna oprema (nad
5000 ECU) potrebna za izvedbo projekta
(Available Research Equipment):
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Laboratory for particle detector development at the Experimental
particle physics department of the J. Stefan Institute
· NI
measurements software LabView in PC computer Pentium III, Windows98 operating system
· radioactive
beta electron source Sr-90 (Amersham), multiwire proportional
chamber and plastic scintillators
· multianode
photomultipliers Hamamatsu, R5900-M16 in
R5900-M4
· amplifier,
shaper and discriminator ASD8
· Gas
system with the gases needed for MWPC operation
· Measurement
units CAMAC and NIM with :
· CAEN
4CH HV Power Supply Mod. N470
· Voltcraft
LV Power Supply
· CAEN
CAENET Camac controller Mod. C117B
· LeCroy
8901A GPIB interface
· Ortec
ADC Mod. AD811 in LeCroy ADC 2249A
· LeCroy
TDC 4291B
· CAEN
16 CH Multiplexed DAC Mod. C221
· CAEN
16 CH ECL scaler Mod. C257
· CAEN
Preset Counter and Gate Mod. C423
· Philips
7106 16 Channel Discriminator Latch
· CAEN
Quad Scaler and Preset Counter Mod. N145
· EG-G-ESN
Octal CF discriminator CF800
· Philips
scientific Quad Linear Fan In-Out Mod.744
· Philips
scientific Quad Two Fold Logic Unit Mod. 752
· Ortec
Fast Amplifier FTA 820A
· Philips
scientific Dual Delay Module Mod.792
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2.6.2. Manjkajoča raziskovalna oprema (nad
5000 ECU) potrebna za izvajanje projekta
(Required Research Equipment):
3. Mednarodno
sodelovanje (International Cooperation)
3.1. Sodelovanje
v mednarodnih projektih (Participation in International Projects):
3.2. Druge
oblike sodelovanja (Other Forms of Cooperation):
4. Projektna
skupina (Project Team) (glej prilogi A in B)
4.1. Odgovorni
nosilec (Principal Researcher)
4.1.1. Ime
in priimek, akademski ter znanstveno-raziskovalni naziv odgovornega nosilca
(Name, Degree):
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Dr. Rok Pestotnik, research assistant holding a PhD
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4.1.2. Kratka
biografija odgovornega nosilca
(CV of the Principal Researcher):
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Dr Rok Pestotnik was born in 1972 in Ljubljana. He won
the first price on the federal physics competition in Decani, Serbia, in
1986. After finishing the primary school, high school and military service,
he studied physics at the University
of Ljubljana, Faculty for mathematics and physics. He graduated in 1996 with
the diploma thesis Multianode photomultiplier as position sensitive detector
of Cherenkov photons. The thesis was awarded with the Preseren's award for
students of the Faculty of mathematics and physics (1996). For his PhD he studied elementary particle and nuclear physics. He defended his PhD
thesis Identification of Pions, Kaons
and Protons in the HERA-B spectrometer at the beginning of 2001. During his
PhD studies he was employed at the University of Ljubljana, Faculty of
mathematics and physics, as a research assistant. Since April 2001 he is
employed at the Institut Jožef Stefan. Since 1999 he has a teaching assistent
position at the University of Ljubljana, Faculty of mathematics and Physics.
The fields of research
of Dr Rok Pestotnik are experimetal elementary particle physics and the
development of detection methods for
the elementary particle identification. As a member of the international
collaboration he collaborates at the HERA-B experiment. The aim of the HERA-B
experiment are studies of rare decays in physics of D and B mesons. He collaborated in the development of photon detectors and electronics for
the Ring Imaging Cherenkov counter in the HERA-B experiment. During his PhD
studies he spent more than a year at the institute DESY, Hamburg. In addition
to the experience in experimental particle physics, he has a broad
experiencies in modelling of physical processes and related software
development.
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4.2. Reference odgovornega nosilca in ostalih
raziskovalcev projektne skupine
(Professional References of the Members of the Project Team)
-
priložite izpise bibliografij iz COBISS-a oz. za medicino iz baze IBMI za
obdobje od 1998 dalje
4.2.1. Navedite
seznam člankov odgovornega nosilca v mednarodno priznanih publikacijah
(samo toliko, da se vidi izpolnjevanje
pogoja)
( List of Scientific Articles of Principal Researcher Published in
Internationally Recognized Publications ):
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See the attached bibliography. Note that Principal Researcher is younger than 35 and he
defended his PhD thesis in 2001.
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4.2.2. Navedite seznam člankov v mednarodno
priznanih publikacijah za tretjino raziskovalcev v projektni skupini, ki
izpolnjuje pogoje za odgovornega nosilca:
(samo toliko, da se vidi izpolnjevanje
pogoja)2
(List of Scientific Articles Published in Internationally Recognized Publications of Qualified
Researchers in the Team):
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See the attached bibliography. Nota that both
researchers are younger than 35 and they both defended their theses in 2001.
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4.2.3. Navedite najbolj citiran članek
odgovornega nosilca citiran v mednarodno priznanih publikacijah v zadnjih 10
letih, število citatov te publikacije
in vir informacije o citatih (CAS, ISI, SSCI, AHCI, itd.)
(The Most Frequently Cited Article of
Principal Researcher in Internationally
Recognized Publications in Last
10 Years, Number of Citations and Citation Source):
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S.Korpar et al., The HERA-B RICH, Nucl. Instr. Meth.A433 (1999)
128-135, 7 citations , source: ISI
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4.2.4. Navedite
najbolj citiran članek za tisto tretjino raziskovalcev v projektni
skupini, ki izpolnjuje z zakonom in pravilnikom določene pogoje za
odgovornega nosilca – citiranih v mednarodno priznanih publikacijah v zadnjih
10 letih, število citatov te publikacije
in vir informacije o citatih (CAS, ISI, SSCI, AHCI, itd.)
(The Most Frequently Cited Article of Project Team in Internationally
Recognized Publications in Last
10 Years, Number of Citations and Citation Source):
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Albrecht H. et al., Evidence for Lambda(c)(2593)(+)
production, Phys. Lett. B 402 (1997) 207-212, 4 citations, source:ISI
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4.3. Navedite mednarodne patente katerih avtor
(soavtor) je odgovorni nosilec in tretjina raziskovalcev v projektni skupini,
ki izpolnjuje z zakonom in pravilnikom
določene pogoje za odgovornega nosilca (International Patents of Project
Team):
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V
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Ljubljani
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, dne
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23.4.2001
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Odgovorni
nosilec:
(Principal
Researcher)
Rok Pestotnik
18. člen Pravilnika o
pogojih in metodologiji izbora in financiranja projektov temeljnega in
aplikativnega raziskovanja: 18. člen
Znanstveno zmožnost raziskovalcev
za izvedbo predlogov projektov temeljnega in aplikativnega raziskovanja se
oceni z vidika:
- znanstvene utemeljenosti
predloga projekta;
- raziskovalne usposobljenosti
projektne skupine.
Projektna skupina izkazuje
usposobljenost, če:
1. odgovorni nosilec izpolnjuje z zakonom določene pogoje za
odgovornega nosilca in:
-
ima
vsaj en članek kot edini avtor, objavljen v mednarodno priznani
publikaciji v zadnjih treh letih ali ustrezno število člankov v
soavtorstvu,
-
je
bil citiran v mednarodno priznanih publikacijah v zadnjih desetih letih, ali
-
ima
mednarodne patente.
Navedene
zahteve ne veljajo za odgovorne nosilce projektov, ki so mlajši od 35 let in od
zagovora njihovega doktorata niso potekla več kot tri leta.
2. vsaj ena tretjina aktivnih raziskovalcev v projektni skupini
izpolnjuje z zakonom in s tem pravilnikom določene pogoje za odgovornega
nosilca,
3. oprema raziskovalne skupine zagotavlja izvedbo projekta.
Znanstveno-raziskovalni sveti
natančneje določijo pogoje iz tega člena.