| 1. |
- Poley, L., et al.
(författare)
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The ABC130 barrel module prototyping programme for the ATLAS strip tracker
- 2020
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Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221 .- 1748-0221. ; 15:9
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Tidskriftsartikel (refereegranskat)abstract
- For the Phase-II Upgrade of the ATLAS Detector [1], its Inner Detector, consisting of silicon pixel, silicon strip and transition radiation sub-detectors, will be replaced with an all new 100% silicon tracker, composed of a pixel tracker at inner radii and a strip tracker at outer radii. The future ATLAS strip tracker will include 11,000 silicon sensor modules in the central region (barrel) and 7,000 modules in the forward region (end-caps), which are foreseen to be constructed over a period of 3.5 years. The construction of each module consists of a series of assembly and quality control steps, which were engineered to be identical for all production sites. In order to develop the tooling and procedures for assembly and testing of these modules, two series of major prototyping programs were conducted: an early program using readout chips designed using a 250 nm fabrication process (ABCN-250) [2, 3] and a subsequent program using a follow-up chip set made using 130 nm processing (ABC130 and HCC130 chips). This second generation of readout chips was used for an extensive prototyping program that produced around 100 barrel-type modules and contributed significantly to the development of the final module layout. This paper gives an overview of the components used in ABC130 barrel modules, their assembly procedure and findings resulting from their tests.
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| 2. |
- Park, Joochun, et al.
(författare)
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Toward the limit of nuclear binding on the N = Z line : Spectroscopy of Cd-96
- 2019
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Ingår i: Physical Review C. - : AMER PHYSICAL SOC. - 2469-9985 .- 2469-9993. ; 99:2
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Tidskriftsartikel (refereegranskat)abstract
- A gamma -decaying isomeric state (tau(1/2) = 197(-17)(+19) ns) has been identified in Cd-96, which is one alpha particle away from the last known bound N = Z nucleus, Sn-100. Comparison of the results with shell-model calculations has allowed a tentative experimental level scheme to be deduced and the isomer to be interpreted as a medium-spin negative-parity spin trap based on the coupling of isoscalar (T = 0) and isovector (T = 1) neutron-proton pairs. The data also suggest evidence for the population of a 9(+) T = 1 state, which is predicted by shell-model calculations to be yrast. Such a low-lying T = 1 state, which is unknown in lighter mass even-even self-conjugate nuclei, can also be interpreted in terms of the coupling of T = 0 and T = 1 neutron-proton pairs.
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| 3. |
- Schlegel, C, et al.
(författare)
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K-isomers in very neutron-rich nuclei around mass 180
- 2000
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Ingår i: Physica Scripta. Topical Issues. - 0281-1847. ; T88, s. 72-76
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Tidskriftsartikel (refereegranskat)abstract
- gamma-spectroscopy methods have been used to search for microsecond isomers among the fragmentation products of a 1 GeV/nucleon Pb-208 beam. In particular the population of the known K-pi = 35/2(-) isomer in W-179 has been investigated and several new isomeric decays have been found for neutron rich nuclei in the A approximate to 180-200 mass region. The ground state band of the neutron rich N = 116 system of W-190 has been identified for the first time and we discuss its structure in comparison to neighboring systems.
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| 4. |
- Sguazzin, M., et al.
(författare)
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Indirect measurements of neutron -induced reaction cross sections at heavy -ion storage rings
- 2023
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Ingår i: 15TH INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, ND2022. - 2100-014X. ; 284
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Konferensbidrag (refereegranskat)abstract
- Neutron-induced reaction cross sections of unstable nuclei are essential for understanding the synthesis of heavy elements in stars and for applications in nuclear technology. However, their measurement is very complicated due to the radioactivity of the targets involved. We propose to circumvent this problem by using the surrogate reaction method in inverse kinematics, where the nucleus formed in the neutroninduced reaction of interest is produced by a reaction involving a radioactive heavy -ion beam and a stable, light target nucleus. The probabilities as a function of the compound -nucleus excitation energy for y -ray emission, neutron emission and fission, which can be measured with the surrogate reaction, are particularly useful to constrain model parameters and to obtain more accurate predictions of the neutron-induced reaction cross sections of interest. Yet, the full development of the surrogate method is hampered by numerous longstanding target issues, which can be solved by combining surrogate reactions with the unique and largely unexplored possibilities at heavy -ion storage rings. In this contribution, we describe the developments we are carrying out to measure for the first time simultaneously y-ray emission, neutron emission and fission probabilities at the storage rings of the GSI/FAIR facility. In particular, we will present the first results of the proof of principle experiment, which we performed in June 2022 at the Experimental Storage Ring (ESR)
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| 5. |
- Sguazzin, M., et al.
(författare)
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Indirect measurements of neutron-induced reaction cross sections at storage rings
- 2023
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Ingår i: NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022. - : EDP Sciences. - 2100-014X. ; 279
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Konferensbidrag (refereegranskat)abstract
- Neutron-induced reaction cross sections of unstable nuclei are essential for understanding the synthesis of heavy elements in stars. However, their measurement is very difficult due to the radioactivity of the targets involved. We propose to circumvent this problem by using for the first time the surrogate reaction method in inverse kinematics at heavy-ion storage rings. In this contribution, we describe the developments we have done to perform surrogate-reaction studies at the storage rings of GSI/FAIR. In particular, we present the first results of the proof of principle experiment, which we conducted recently at the Experimental Storage Ring (ESR).
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| 6. |
- Giovinazzo, J., et al.
(författare)
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4D-imaging of drip-line radioactivity by detecting proton emission from 54mNi pictured with ACTAR TPC
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Proton radioactivity was discovered exactly 50 years ago. First, this nuclear decay mode sets the limit of existence on the nuclear landscape on the neutron-deficient side. Second, it comprises fundamental aspects of both quantum tunnelling as well as the coupling of (quasi)bound quantum states with the continuum in mesoscopic systems such as the atomic nucleus. Theoretical approaches can start either from bound-state nuclear shell-model theory or from resonance scattering. Thus, proton-radioactivity guides merging these types of theoretical approaches, which is of broader relevance for any few-body quantum system. Here, we report experimental measurements of proton-emission branches from an isomeric state in 54mNi, which were visualized in four dimensions in a newly developed detector. We show that these decays, which carry an unusually high angular momentum, ℓ = 5 and ℓ = 7, respectively, can be approximated theoretically with a potential model for the proton barrier penetration and a shell-model calculation for the overlap of the initial and final wave functions.
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| 7. |
- Giovinazzo, J., et al.
(författare)
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Proton 3D tracking and emission time from a short-lived isomer with ACTAR TPC
- 2022
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 1042
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Tidskriftsartikel (refereegranskat)abstract
- An experiment was conducted at the GANIL/LISE3 facility to produce the 10+ isomer of 54Ni and measure its proton radioactivity decay branches. The proton detection was achieved with the ACTAR TPC device that enabled the separation of the small signal of the emitted proton from the large signal of the implanted ion, while the decay half-life is of the order of 150 ns. From the measured data, the emitted proton track length and the decay time of the ion can be extracted simultaneously. The full proton radioactivity pattern could be established, with two emission branches and their relative branching ratio. Data processing and analysis that allowed to identify and separate the ion and the proton signals in order to reconstruct the particles trajectories and decay time are detailed. The evaluation of the detection efficiency for the proton radioactivity branches based on a full simulation is described.
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| 8. |
- Rudolph, D., et al.
(författare)
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Mirror symmetry at mass A = 54: E4 effective charges near doubly magic 56Ni
- 2022
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 830
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Tidskriftsartikel (refereegranskat)abstract
- Proton-emission branches of the 10+ isomer in the Tz=−1 nucleus 54Ni have been imaged with the active target and time projection chamber (ACTAR TPC) in an experiment conducted at the Grand Accélérateur National d'Ions Lourds (GANIL). The completed decay scheme allows derivation of the reduced transition strengths, B(E2;10+→8+) and B(E4;10+→6+), for the two competing γ-ray transitions. By means of a comparison with their well-known ‘mirror transitions’ in Tz=+1 54Fe, and aided by a variety of shell-model calculations in the fp model space, effective charges for E4 transitions near N=Z 56Ni can be deduced: επ≈1.40 and εν≈0.30. Mirror-energy differences are explored with various shell-model interactions and isospin-symmetry breaking terms.
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| 9. |
- Sguazzin, M., et al.
(författare)
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Determining neutron-induced reaction cross sections through surrogate reactions at storage rings
- 2023
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Ingår i: Journal of Physics: Conference Series. - 1742-6588 .- 1742-6596. ; 2586:1
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Konferensbidrag (refereegranskat)abstract
- Determining the cross sections of neutron-induced reactions on short-lived nuclei is imperative to rate calculations in stellar nucleosynthesis and applications of nuclear physics. It is also an immense experimental challenge due to the radioactivity of the targets involved. Our goal is to circumvent this obstacle by using surrogate reactions in inverse kinematics at the heavy-ion storage rings of GSI/FAIR. We present here preliminary results from the first proof of principle experiment, where a beam of 208Pb impinged on a H2 gas jet target in the Experimental Storage Ring (ESR).
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| 10. |
- Koldste, G. T., et al.
(författare)
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Multiparticle emission in the decay of Ar-31
- 2014
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 89:6
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Tidskriftsartikel (refereegranskat)abstract
- A multihit capacity setup was used to study the decay of the dripline nucleus Ar-31, produced at the ISOLDE facility at CERN. A spectroscopic analysis of the beta-delayed three-proton decay of Ar-31 is presented for the first time together with a quantitative analysis of the beta-delayed 2p gamma decay. A new method for determination of the spin of low-lying levels in the beta p daughter 30S using proton-proton angular correlations is presented and used to determine that the spin of the 5.2-MeV level is most likely 3(+) with 4(+) also possible. The half-life of Ar-31 is found to be 15.1(3) ms. An improved analysis of the Fermi beta strength including the beta 3p-decay mode gives a total measured branching ratio of 3.60(44)%, which is lower than the theoretical value found to be 4.24(43)%. Finally, a previously unidentified. transition from the isobaric analog state in the decay of Ar-33 has been found.
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