Intro Setup Results Summary
(Ülkemizin ilk fotonükleer reaksiyonu Akdeniz Üniversitesinde
gerçeklestirildi: Madde, Anti-Madde, Saf Enerji ve Simya)
Turkey’s first photonuclear reactionsperformed at Akdeniz University: Matter,Anti-matter, Pure Energy and Alchemy
http://mistug.tubitak.gov.tr/bdyim/kabul.php?dergi=fiz
Haris Ðapo(Ismail Boztosun)
Akdeniz University, Antalya
IZYEF 2013 • Izmir, September 2013
Intro Setup Results Summary
Outline
1 Introduction
2 Method and setup
3 Results
4 Summary and Outlook
Intro Setup Results Summary
Outline
1 Introduction
2 Method and setup
3 Results
4 Summary and Outlook
Intro Setup Results Summary
Introduction
Photonuclear reactions• photonuclear reactions describe a set of interactions
between nuclei and photons, most commonly separation ofeither from the nucleus
• since the realization that nuclei are not fundamentalpoint-like particles (In 1932, James Chadwick discoveredneutron) the possibility of removing a neutron or a protonfrom nucleus arose
• separating a neutron of a proton from stable nucleusrequires several MeV of energy (one commonly needs10 MeV)
• producing a photon of 10 MeV energy took few decades
• most commonly the start of photonuclear reactions isassociated with construction and operation of SLAC(Stanford Linear Accelerator Center) in 1960’s
Intro Setup Results Summary
Nucleide Map
Intro Setup Results Summary
Photonuclear reactions
Various cases• photonuclear reactions change one element into another
(Alchemy)
• if a neutron is removed a proton rich nucleus is createdand it decays via β+ decay back to valley of stability
• β+ decays produce positrons and characteristic anhilationpeak at mass of electron of 511 keV is observed(Anti-Matter)
• proton rich nuclei are not accessible via neutron absorption
• if proton is removes a neutron rich nucleus is created and itdecays via β−
• if photons is absorbed a metastable stable version of thesame element is created
Intro Setup Results Summary
Photonuclear reactions in detail
Generic
γ +NZ A →
N−1Z A − 1 + n
γ +NZ A →
N−1Z A − 1∗ + n
γ +NZ A →
NZ A − 1 + p
Zinc example
γ +64 Zn →63Zn + n
γ +70 Zn →69Zn∗ + n
γ +68 Zn →67Cu + p
Intro Setup Results Summary
Outline
1 Introduction
2 Method and setup
3 Results
4 Summary and Outlook
Intro Setup Results Summary
Experiment stages
Shot description
• first the sample is irradiated in the linac at the AkdenizUniversity’s hospital
• sample is transported from the hospital to the physicsdepartment
• irradiated sample is counted in a detector
• counts are stored at appropriate time intervals
• once the counting is finished, background subtraction isperformed
• background subtracted spectrum is analyzed peak by peak
• transition energies are obtained at this point
• counts from each peak are correlated with the time stamp
• a fit of counts vs. time is performed
• half-life is obtained at this point
Intro Setup Results Summary
Photonuclear reactions with linear accelerators
LINAC• linear accelerators can produce photons by bombarding a
Tungsten, or and high-Z, target with electrons
• photons are than produced trough bremssthralungand have thecharacteristicspectrum
• on the right:bremssthralungspectrumwith 18 MeVend-pointenergy
Intro Setup Results Summary
Linear accelerators
cLINAC• photonuclear experiments involving linacs are routinely
performed around the world
• but the use of clinical linac(cLINAC) for this purpose is anovel concept
• modern cLINAC found in radiation treatment facilities arecapable of producing bremsstrahlung photons withendpoint energies up to 25 MeV and compare well tospecialist setups such as S-DALINAC at TU Darmstadt orELBE at Forschungszentrum Dresden in Rossendorf
• for the most part photonuclear measurement are notincluded in NUDAT, especially so for intermediate massnuclei
11pioneering experiment on gold: P. Mohr, S. Brieger, G. Witucki, and M.
Maetz, Nucl.Instrum.Meth. A580, 1201 (2007), 0707.2933.
Intro Setup Results Summary
Our linac setup
Philips SLi-25
• current end-point energy is 18 MeV, although linac canoperate at lower energies as well
• in the future we plan to bring online 25 MeV end-pointenergy
• primary electron beam is generated by a gun with anenergy of 50 keV
• electrons are accelerated in a copper cavity by a 30 GHzradio-frequency with peak power of about 5 MW
• steering and focusing of the beam is achieved by standardmagnetic and electrostatic devices
• beam current is 30 µA for 18 MeV
• once collimated and flattened at a distance of 100 cm, themaximum area covered by photons is 40×40 cm2
Intro Setup Results Summary
Linac schematic
Intro Setup Results Summary
The detector
High Purity Germanium Detector(HPGe)
• p-type, coaxial, electrically cooled, HPGe gamma-rayspectrometer with 40% relative efficiency and 768 eVFWHM at 122 keV for 57Co and 1.85 keV FWHM at1332 keV for 60Co
• samples and the detector, were placed into a well-shieldedcavity
• the detector is connected to the usual NuclearInstrumentation Module for data acquisition
• calibration was performed with a source supplied by theÇekmece Nuclear Research and Training Center
• detector was configured with 8192 channels and theresulting energy resolution was 0.33954 keV (currently16383 channels and 0.169 keV resolution)
Intro Setup Results Summary
Full reactions
Generic
γ +NZ A →
N−1Z A − 1 + n
N−1Z A − 1 →
NZ−1A − 1∗ + e+ + ν
NZ−1A − 1∗
→NZ−1A − 1 + γ
γ +NZ A →
N−1Z A − 1∗ + n
N−1Z A − 1∗
→N−1Z A − 1 + γ
γ +NZ A →
NZ−1A − 1 + p
NZ−1A − 1 →
N−1Z A − 1∗ + e− + ν
N−1Z A − 1∗
→N−1Z A − 1 + γ
Zinc example
γ +64 Zn →63Zn + n
63Zn →63Cu∗ + e+ + ν
63Cu∗→
63Cu + γ
γ +70 Zn →69Zn∗ + n
69Zn∗→
69Zn + γ
γ +68 Zn →67Cu + p
67Cu →67Zn∗ + e + ν
67Zn∗→
67Zn + γ
γ +66 Zn →65Zn + n
65Zn →65Cu∗ + e+ + ν
65Cu∗→
65Cu + γ
Intro Setup Results Summary
The observations
The description of detection
A stable element is exposed to linac gamma-rays. A radioactiveelement is produced. The element decays trough gamma orbeta decay. Gamma decay is directly observed. In case of betadecay daughter nuclei are created in excited states and thanthe daughter decays trough gamma-decay to its ground state.The time-dependance of decay is linked to the half-life of theparent. In all cases only gamma-transition are observed.
Notes• in principle all nuclei go trough photonuclear reactions, but
only those whose neighbor is radioactive can be observedin our setup
• in addition more practical restrictions apply, like: length ofhalf-life, observability of daughter states, etc.
Intro Setup Results Summary
The analysis tool
GF3• GF3 is a least-squares peak-fitting program designed
primarily for use in analyzing gamma-ray spectra fromGermanium detectors
• GF3 fits three components to each peak: a Gaussian, askewed Gaussian and a smoothed step function toincrease the background on the low-energy side
• the Gaussian, is the main component of the peak
• the skewed Gaussian, arises fromincomplete charge collection
• the step function arises mainlyfrom Compton scattering ofphotons into the detector andfrom escape of photoelectronsfrom the Ge crystal
Intro Setup Results Summary
Outline
1 Introduction
2 Method and setup
3 Results
4 Summary and Outlook
Intro Setup Results Summary
Cu-63 transition energies
Data• NUDAT: 669.62±0.05 keV;
962.06±0.04 keV
• Our result:669.58±0.02keV and 962.10±0.02 keV
100
101
102
103
104
665 670
Cou
nts
per
keV
E[keV]
t=2315 st=700 st=140 s
955 960 965
E[keV]
t=2315 st=700 st=140 s
Intro Setup Results Summary
Zn-63 decay curve
0
2000
4000
6000
8000
10000
12000
14000
0 250 500 750 1000 1250 1500 1750 2000 2250
Net
cou
nts
t[s]
669 keV962 keVfit(669),N0=27.4e3,λ=2.83e-3fit(962),N0=14.2e3,λ=3.34e-3
Data• NUDAT: 38.47±0.05 min
• Our result: 40.8±0.6 min (669 peak)and 34.6±0.7 min (962 peak)
Intro Setup Results Summary
Zn-67 transition energies
Data• NUDAT: 184.577±0.010
keV; 300.219±0.010 keV
• Our measurement:184.273±0.005 keV;300.04±0.23 keV
102
103
104
105
184 186
Cou
nts
per
keV
E[keV]
t=86126 st=23703 st=4837 s
298 300
E[keV]
t=86126 st=23703 st=4837 s
Intro Setup Results Summary
Cu-67 decay curve
0
50000
100000
150000
200000
250000
0 10000 20000 30000 40000 50000 60000 70000 80000 90000
Net
are
a
t[s]
x50
184 keV300 keVfit(184),N0=98.8e4,λ=3.19e-6fit(300),N0=3.3e4,λ=9.9e-7
Data• NUDAT: 61.83±0.12 h
• Our result: 60.3±0.6 h (184 peak)and 197±73 h (300 peak)
Intro Setup Results Summary
Zn-69m and Cu-65 transition energies
100
101
102
103
104
105
435 440
Cou
nts
per
keV
E[keV]
t=86126 st=23703 st=4837 s
1110 1115 1120
E[keV]
t=86126 st=23703 st=4837 s
Data• NUDAT:
438.614±0.018 keV; 1115.546±0.004 keV
• Our:438.512±0.005 keV; 1115.696±0.008 keV
Intro Setup Results Summary
Zu-69m decay rate
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
0 10000 20000 30000 40000 50000 60000 70000 80000 90000
Net
are
a
t[s]
438 keVfit(438),N0=63.30e4,λ=14.23e-6
Data• NUDAT: 13.74±0.02 h
• Our result: 13.51±0.03 h
Intro Setup Results Summary
Zu-65 decay rate
0
50000
100000
150000
200000
250000
0 10000 20000 30000 40000 50000 60000 70000 80000 90000
Net
are
a
t[s]
1115 keVfit(438),(N0*λ)=2.462
Data• NUDAT: 243.93±0.09 days
• Only 1 day of observation is not sufficient for 244 daydecay
Intro Setup Results Summary
Outline
1 Introduction
2 Method and setup
3 Results
4 Summary and Outlook
Intro Setup Results Summary
Summary
The road so far• photonuclear reactions with cLINAC are real possibility
• first experiment of photonuclear reaction performed inTurkey
• performed with local resources, staff and capabilities
• at the very first attempt data accuracy was reasonable
• and with every day we are getting better
• but the real testament to our achievement and a realsummary is all the data we have gathered and shown
Intro Setup Results Summary
Summary
The road so far• photonuclear reactions with cLINAC are real possibility
• first experiment of photonuclear reaction performed inTurkey
• performed with local resources, staff and capabilities
• at the very first attempt data accuracy was reasonable
• and with every day we are getting better
• but the real testament to our achievement and a realsummary is all the data we have gathered and shown
What did not fit into the talk• since may we have performed several new experiments on
various nuclei
• Cu, Ni, Ti, Pb, In, Hg, etc.
• but the hard part, the data analysis is still pending
Intro Setup Results Summary
Outlook
To be continued, stay tuned
• solve the systematic accuracy issue
• find new elements which would be best suited for futureexperiments
• upgrade the accelerator to 25 MeV (software issue)
• build an online multi detector setup capable of measuring(γ, γ′) reactions
• with new setup investigate the collective behavior of nuclei(GDR, PDR, etc.)
Intro Setup Results Summary
Our group
Collaborators on this project:Ismail Boztosun,Haris Ðapo, Süleyman Fatih Özmen,Yigit Çecen, Mesut Karakoç, Abdullah Çoban,Alp Cesur,Tanfer Caner, Edip Bayram, Gizem B. Keller, Beyza Kücük,Abdullah Güvendi,Melek Derman and Deniz Kaya
Intro Setup Results Summary
Thank you for yourattention!