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LIFETIME MEASUREMENTS WITH THE DOPPLER SHIFT ATTENUATION METHOD USING A THICK HOMOGENEOUS PRODUCTION TARGET - VERIFICATION OF THE METHOD
KTH, School of Engineering Sciences (SCI), Physics. Istanbul University Vezneciler/Fatih, Istanbul, Turkey.
KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.ORCID iD: 0000-0003-1771-2656
KTH, School of Engineering Sciences (SCI), Physics.ORCID iD: 0000-0001-9741-141x
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2017 (English)In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 48, no 3, p. 325-329Article in journal (Refereed) Published
Abstract [en]

Doppler Shift Attenuation Method (DSAM) analysis of excited-state lifetimes normally employs thin production targets mounted on a thick stopper foil ("backing") serving to slow down and stop the recoiling nuclei of interest in a well-defined manner. Use of a thick, homogeneous production target leads to a more complex analysis as it results in a substantial decrease in the energy of the incident projectile which traverses the target with an associated change in the production cross section of the residues as a function of penetration depth. Here, a DSAM lifetime analysis using a thick homogeneous target has been verified using the Doppler broadened lineshapes of gamma rays following the decay of highly excited states in the semi-magic (N = 50) nucleus Ru-94. Lifetimes of excited states in the Ru-94 nucleus have been obtained using a modified version of the LINESHAPE package from the Doppler broadened lineshapes resulting from the emission of the gamma rays, while the residual nuclei were slowing down in the thick (6 mg/cm(2)) metallic Ni-58 target. The results have been validated by comparison with a previous measurement using a different (RDDS) technique.

Place, publisher, year, edition, pages
Jagiellonian University Press, 2017. Vol. 48, no 3, p. 325-329
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-206296DOI: 10.5506/APhysPolB.48.325ISI: 000398717500013Scopus ID: 2-s2.0-85017146840OAI: oai:DiVA.org:kth-206296DiVA, id: diva2:1093564
Conference
Zakopane Conference on Nuclear Physics - Extremes of the Nuclear Landscape, AUG 28-SEP 04, 2016, Zakopane, POLAND
Note

QC 20170508

Available from: 2017-05-08 Created: 2017-05-08 Last updated: 2024-03-18Bibliographically approved
In thesis
1. Lifetime Measurements of Excited States in the Semi-Magic Nucleus 94Ru
Open this publication in new window or tab >>Lifetime Measurements of Excited States in the Semi-Magic Nucleus 94Ru
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Lifetimes of highly excited states in the semi-magic (N=50) nucleus 94Ru were deduced from an analysis of the Doppler broadened transition line shapes. Excited states in 94Ru were populated in the 58Ni(40Ca, 4p)94Ru fusion-evaporation reaction at the Grand Accélérateur National d’Ions Lourds (GANIL) accelerator complex situated in Caen, France. Doppler Shift Attenuation Method (DSAM) lifetime analysis was performed on the Doppler broadened peaks in energy spectra from γ-rays emitted while the residual nuclei were slowing down in a thick 6 mg/cm2 metallic 58Ni target. In total eight excited-state lifetimes in the angular momentum range I = (13 − 20)ħ have been measured, five of which were determined for the first time. The deduced corresponding B(M1) and B(E2) reduced transition strengths are discussed within the framework of large-scale shell model calculations.

Abstract [sv]

Livstider för exciterade tillstånd i den semimagiska (N = 50) atomkärnan 94Ru har uppmätts från en analys av Doppler-breddade övergångslinjer. Exciterade tillstånd i 94Ru har populerats i 58Ni(40Ca, 4p)94Ru fusion-evaporationsreaktioner vid partikelacceleratorn Grand Accélérateur National d’Ions Lourds (GANIL), Caen, Frankrike. Livstidsanalys utfördes med hjälp av Dopplerskiftsattenueringsmetoden (DSAM) på linjer i energispektra uppmätta från gammastrålning som emitterades medan de högt exciterade atomkärnorna bromsades ned i ett homogent metalliskt strålmål av 6 mg/cm2 tjocklek. Mätmetoden har verifierats med hjälp av data från en mätning utförd med en alternativ metod. Livstider för sammanlagt åtta exciterade tillstånd i spinn-intervallet I = (13 − 20)ħ har uppmätts, varav fem bestämdes för första gången. Ur dessa har härletts B(M1) och B(E2) övergångssannolikheter vilka diskuteras inom ramen för storskaliga skalmodellsberäkningar.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. p. 33
Series
TRITA-FYS, ISSN 0280-316X ; 2017:73
Keywords
nuclear structure, lifetime measurements, doppler shift attenuation method, thick target
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-217356 (URN)978-91-7729-601-0 (ISBN)
Presentation
2017-11-23, FB-55, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 14:00 (English)
Opponent
Supervisors
Note

QC 20171110

Available from: 2017-11-10 Created: 2017-11-09 Last updated: 2022-06-26Bibliographically approved
2. Experimental Studies of the Neutron Deficient Atomic Nuclei 94Ru, 95Rh and 172Pt via their Electromagnetic Properties: Du som saknar dator/datorvana kan kontakta Pär Olsson, polsson@kth.se för information
Open this publication in new window or tab >>Experimental Studies of the Neutron Deficient Atomic Nuclei 94Ru, 95Rh and 172Pt via their Electromagnetic Properties: Du som saknar dator/datorvana kan kontakta Pär Olsson, polsson@kth.se för information
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis reports new results obtained from studies of the neutron deficient atomic nuclei 94Ru, 95Rh and 172Pt using two different experimental set-ups. In the first part, lifetimes of highly excited states in nuclei near the N=50 closed-shell (94Ru and 95Rh) were deduced from an analysis of the Doppler broadened transition lineshapes measured following the 58Ni(40Ca,4p) and 58Ni(40Ca,3p) fusion-evaporation reactions at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator complex situated in Caen, France. Doppler Shift Attenuation Method (DSAM) lifetime analysis was performed on the Doppler broadened peaks in energy spectra from γ-rays emitted from excited states in the nuclei of interest while they were slowing down in a thick 6 mg/cm2 metallic 58Ni target. For 94Ru, eight excited-state lifetimes in the angular momentum range I= (13-20)h have been measured in total, five of which were determined for the first time. For the lifetime analysis of 95Rh, three lifetime values have been obtained. One of them, the lifetime of the 39/21- excited state, has been measured for the first time. In the other cases, the lifetimes of the previously measured 29/22- and 37/21- excited states have been obtained. The corresponding B(M1) and B(E2) reduced transition strengths have been deduced and are discussed within the framework of large-scale shell model (LSSM) calculations. In the second part, the extremely neutron deficient 172Pt nucleus has been studied. Excited states in 172Pt were populated using the 96Ru(78Kr,2p) and 92Mo(83Kr,3n) reactions at the Accelerator Laboratory of the University of Jyväskylä (JYFL), Finland. Prompt γ-rays were detected using the JUROGAM high-purity germanium detector array at the target position while the identification and decay spectroscopy of 172Pt was performed using the RITU gas-filled separator in conjunction with the GREAT spectrometer. The Recoil Decay Tagging (RDT) technique was used for the selection of prompt γ-rays. The known positive-parity band has been extended and the negative-parity structure has been established on top of the lowest member of the negative parity band which has now been firmly assigned as spin-parity 3-. Moreover, the newly observed E3 transition provides a link between the negative parity band with the ground state. The observations of this E3 transition together with several E1 transitions connecting the negative-parity structure with the ground-state band is consistent with the presence of octupole collectivity in 172Pt. Furthermore, this is the first observation of an E3 transition connecting the negative parity band with the ground-state band in the Pt-Os-W region. The experimental results were interpreted in terms of LSSM and total routhian surface calculations. With the support of these theoretical calculations, evidence for octupole collectivity in 172Pt is proposed.

Abstract [sv]

Denna avhandling beskriver resultat från studier av de neutronfattiga isotoperna rutenium-94 (94Ru), rodium-95 (95Rh) och platina-172 (172Pt). Den första delen av avhandlingen behandlar livstidsmätningar för högt exciterade tillstånd i kärnorna 94Ru och 95Rh med antalat neutroner, N, = 50 vilket motsvarar ett slutet skal i den modell för atomkärnors struktur som benämns skalmodellen. Livstider för 94Ru och 95Rh härleddes från en analys av Dopplerbreddade övergångslinjer uppmätta efter det att kärnorna skapats i fusion mellan jonstrålar av kalcium-40 och strålmål bestående av nickel-58. Experimentet utfördes vid den franska acceleratoranläggningen Grand Accelerateur National d'Ions Lourds (GANIL). Gammastrålning uppmättes med germaniumdetektorsystemet EXOGAM medan elektriskt laddade partiklar och neutroner som utsändes i anslutning till fusionsreaktionerna registrerades i CsI-detektorsystemet DIAMANT respektive neutron detektorsystemet Neutron Wall. För 94Ru har livstider uppmätts för åtta exciterade tillstånd med spinn i intervallet I= 13-20h. För fem av dessa bestämdes livstiden för första gången. För 95Rh har tre livstidsvärden erhållits. För ett av dem, 39/21-, har livstiden uppmättts för första gången i detta arbete. I de tvä andra fallen (37/21- och 29/22-) var livstiden känd sedan tidigare men har nu uppmätts med högre precision. De reducerade övergångssannolikheterna för magnetiska dipolövergångar och elektriska kvadrupolövergångar (B(M1) respektive B(E2)) från dessa tillstånd har härletts från de uppmätta livstiderna samt förgreningsförhållanden för de relevanta elektromagnetiska övergångarna. Dessa jämförs med och diskuteras inom ramen för storskaliga skalmodellsberäkningar (LSSM). I den andra delen av avhandlingsarbetet har den extremt neutronfattiga atomkärnan 172Pt studerats. Exciterade tillstånd i 172Pt populerades i fusionsreaktionerna 96Ru(78Kr, 2p)172Pt* och 92Mo(83Kr, 3n)172Pt* mellan jonstrålar av kryptonisotoperna med masstal 78 och 83 och strålmål bestående av tunna folier av rutenium-96 respektive molybden-92. Dessa experiment utfördes vid Acceleratorlaboratoriet vid universitetet i Jyväskylä (JYFL), Finland. Prompt gammastrålning detekterades med germaniumdetektorsystemet JUROGAM vilket var placerat i anslutning till strålmålet. Sönderfallsspektroskopi av 172Pt och andra neutronfattiga fusionsprodukter utfördes i fördröjd koincidens mellan JUROGAM och spektrometern för radioaktiva sönderfall, GREAT efter att de hade passerat den gasfyllda elektromagnetiska rekylseparatorn RITU. Den s.k. Recoil Decay Tagging (RDT)-tekniken användes för identifiering av de sällsynta 172Pt-kärnorna. På detta sätt kunde den kända strukturen av exciterade tillstånd i 172Pt och elektromagnetiska övergångar mellan dessa tillstånd och till grundtillståndet utökas. I synnerhet har ett lågt liggande tillstånd med spin-paritet 3- fastställts och sönderfallet mellan detta tillstånd och grundtillståndet observerats. Bl.a. egenskaperna hos denna gammaövergång med multipolaritet E3 stöder teoretiska förutsägelser om att atomkärnan 172Pt uppvisar oktupolkollektivitet dvs. kan exciteras från grundtillståndet till ett oktupolvibrationellt tillstånd.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2020. p. 60
Series
TRITA-SCI-FOU ; 2020:07
National Category
Physical Sciences
Research subject
Physics, Atomic, Subatomic and Astrophysics
Identifiers
urn:nbn:se:kth:diva-271771 (URN)978-91-7873-484-9 (ISBN)
Public defence
2020-04-23, Via Zoom: https://kth-se.zoom.us/webinar/register/WN_ZIbDpWsxSSql98O0C4TBxA, 14:00 (English)
Opponent
Supervisors
Available from: 2020-04-07 Created: 2020-04-07 Last updated: 2022-06-26Bibliographically approved

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Ertoprak, AysegulCederwall, BoJakobsson, UlrikaDoncel, MariaAtac, A.Bäck, TorbjörnGhazi Moradi, Farnaz

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