.
An overview of relevant results on the study of 1
−
states focusing on their excitation with nuclear probes is given. Results obtained for the
90
Zr ,
124
Sn , and
208
Pb nuclei using the (
17
O,
...17
O′γ) reaction are compared with available data obtained with the (γ, γ′, and (p, p′) reactions. These comparisons allow to learn on the nature of the populated states, particularly the E1 states, whose isospin character is presently poorly known. The DWBA description of the data is discussed in terms of different form factors, standard collective form factor and form factors obtained by folding microscopically calculated transition densities. The relevant aspects related to the used theoretical approach are also presented. The main objective of the analyses is the extraction of the values of the fraction of the energy weighted sum rule strength for the isoscalar dipole excitation. For completeness, in all cases, the DWBA analysis was made also for the excitations of 2
+
and 3
−
states.
.
A review of selected experimental works on the gamma-decay from the Giant and Pygmy Dipole Resonances is presented. The common feature of these experiments is that gamma-decay originates from ...dipole states populated using reactions induced by heavy ions. The focus is the investigation of dipole modes built on the ground and excited states. The major developments made during the years regarding the detection of high-energy gamma-rays are briefly discussed together with specific results concerning a chosen number of problems among those that were addressed by the theoretical works of P.F. Bortignon. They are: i) the dipole mode in the initial stages of reactions among heavy ions with different
N
/
Z
values for the target and projectile; ii) the problem of isospin symmetry in nuclei at finite temperature; iii) pygmy states far from stability; iv) the nature of the pygmy states.
We demonstrate the possibility to extract nuclear state femtosecond lifetimes from two-step
γ
ray cascades measured with a Ge-detector array. The technique is based on measuring the Doppler shift of ...a
γ
ray, caused by the recoil of a preceding
γ
ray emission. Since the two
γ
rays are populating/de-populating the same state they form a start/stop signal, the delay of which is compared to the slowing down motion of the nucleus within the target material. A multi-detector array combined with digital acquisition electronics in list mode, allows to measure several angular combinations and two-step cascades efficiently and simultaneously within one single experiment. The concept was demonstrated with the FIPPS array for the
35
Cl(n,
γ
)
36
Cl
reaction, where we obtained good agreement with literature values showing the validity of the method.
Abstract
The structure of the
11
/
2
1
+
state in
131
Sb was investigated at the LOHENGRIN spectrometer of Institut Laue-Langevin via neutron-induced fission of
235
U and lifetime measurements, ...yielding
T
1
/
2
=
3
(
2
)
, at the edge of the sensitivity of the experimental method. This first result for the
11
/
2
1
+
state half-life in neutron-rich Sb isotopes provides a quadrupole reduced transition probability to the ground state of
B
(
E
2
)
=
1.4
−
0.6
+
1.5
W.u., very close to the
B
(
E
2
;
2
1
+
→
0
1
+
)
in
130
Sn. Realistic shell-model calculations reproduce well both the experimental level scheme of
131
Sb and the
B
(
E
2
;
11
/
2
1
+
→
7
/
2
1
+
)
value, indicting a dominant
2
+
(
130
Sn
)
⊗
π
g
7
/
2
core-proton coupled configuration for the
11
/
2
1
+
state.
AGATA is a modern
γ
-ray spectrometer for in-beam nuclear structure studies, based on
γ
-ray tracking. Since more than a decade, it has been operated performing experimental physics campaigns in ...different international laboratories (LNL, GSI, GANIL). This paper reviews the obtained results concerning the performances of
γ
-ray tracking in AGATA and associated algorithms. We discuss
γ
-ray tracking and algorithms developed for AGATA. Then, we present performance results in terms of efficiency and peak-to-total for AGATA. The importance of the high effective angular resolution of
γ
-ray tracking arrays is emphasised, e.g. with respect to Doppler correction. Finally, we briefly touch upon the subject of
γ
-ray imaging and its connection to
γ
-ray tracking.
Lifetime measurements in 131Sb at LOHENGRIN Bottoni, S.; Gamba, E. R.; De Gregorio, G. ...
Journal of physics. Conference series,
09/2023, Volume:
2586, Issue:
1
Journal Article
Peer reviewed
Open access
The neutron-rich 131Sb nucleus was studied at Institut Laue-Langevin, with the LOHENGRIN spectrometer, via neutron-induced fission of 235U and lifetime measurements using LaBr3(Ce) detectors. The ...lifetimes of the 11/21+ and 19/21+ states were measured with the generalized centroid difference and the decay slope methods, yielding T½=3(2) ps and T½=1347(171) ps, respectively. The measured value for the 11/21+ is at the limit of the fast-timing technique. The level scheme of 131Sb and the decay properties of the 11/21+ state were described by realistic shell-model calculations, which reproduce well both the experimental spin and energy sequences of 131Sb and the measured B(E2; 11/21+→7/21+) value, pointing to an almost pure 2+(130Sn) ⊗ πg7/2, core-proton coupled configuration for the 11/21+ state.
Conceptual design of the AGATA 2π array at LNL Valiente-Dobón, J.J.; Goasduff, A.; Balogh, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2023, Volume:
1049
Journal Article
Peer reviewed
The Advanced GAmma Tracking Array (AGATA) has been installed at Laboratori Nazionali di Legnaro (LNL), Italy. In this installation, AGATA will consist, at the beginning, of 13 AGATA triple clusters ...(ATCs) with an angular coverage of 1π, and progressively the number of ATCs will increase up to a 2π angular coverage. This setup will exploit both stable and radioactive ion beams delivered by the Tandem–PIAVE-ALPI accelerator complex and the SPES facility. The new implementation of AGATA at LNL will be used in two different configurations, firstly one coupled to the PRISMA large-acceptance magnetic spectrometer and lately a second one at Zero Degrees, along the beam line. These two configurations will allow us to cover a broad physics program, using different reaction mechanisms, such as Coulomb excitation, fusion-evaporation, transfer and fission at energies close to the Coulomb barrier. These setups have been designed to be coupled with a large variety of complementary detectors such as charged particle detectors, neutron detectors, heavy-ion detectors, high-energy γ-ray arrays, cryogenic and gasjet targets and the plunger device for lifetime measurements. We present in this paper the conceptual design, characteristics and performance figures of this implementation of AGATA at LNL.
.
An in-beam test of two pixel-type silicon detectors of the TRACE detector project has been performed at Laboratori Nazionali di Legnaro (Italy). The aim was to investigate the lowest kinetic energy ...values at which isotopic identification of heavy-ion reactions products with mass
A
∼
10
is possible, by using a single-layer silicon detector. Two separate read-out chains, analog and digital, were used, and the Pulse Shape Analysis technique was employed to obtain the particle identification matrices for the digitally processed data. The results confirmed the high capability of the Pulse Shape Analysis method which can be used for light ion identification, with performances similar to the analog approach. Separation in both charge and mass was obtained for Li and Be isotopes, however, the presence of a significant background from alpha particles severely limited the data analysis in the lower energy region. Due to this effect, the identification of the light products (
7, 6
Li isotopes) could be possible down to
∼
24
.
5
MeV only, while the
9, 7
Be isotopes were separable down to
∼
29
MeV. This gives the value of
<
4
MeV/nucleon as the lowest kinetic energy for light products identification by using the pixel-type detectors of the TRACE project, in the present experimental conditions.
Objective
To determine the existence of mutant and variant CYP3A4 alleles in three racial groups and to assess functions of the variant alleles by complementary deoxyribonucleic acid (cDNA) ...expression.
Methods
A bacterial artificial chromosome that contains the complete CYP3A4 gene was isolated and the exons and surrounding introns were directly sequenced to develop primers to polymerase chain reaction (PCR) amplify and sequence the gene from lymphocyte DNA. DNA samples from Chinese, black, and white subjects were screened. Mutating the affected amino acid in the wild‐type cDNA and expressing the variant enzyme with use of the baculovirus system was used to functionally evaluate the variant allele having a missense mutation.
Results
To investigate the existence of mutant and variant CYP3A4 alleles in humans, all 13 exons and the 5′‐flanking region of the human CYP3A4 gene in three racial groups were sequenced and four alleles were identified. An A→G point mutation in the 5′‐flanking region of the human CYP3A4 gene, designated CYP3A4*1B, was found in the three different racial groups. The frequency of this allele in a white population was 4.2%, whereas it was 66.7% in black subjects. The CYP3A4*1B allele was not found in Chinese subjects. A second variant allele, designated CYP3A4*2, having a Ser222Pro change, was found at a frequency of 2.7% in the white population and was absent in the black subjects and Chinese subjects analyzed. Baculovirus‐directed cDNA expression revealed that the CYP3A4*2 P450 had a lower intrinsic clearance for the CYP3A4 substrate nifedipine compared with the wild‐type enzyme but was not significantly different from the wild‐type enzyme for testosterone 6β‐hydroxylation. Another rare allele, designated CYP3A4*3, was found in a single Chinese subject who had a Met445Thr change in the conserved heme‐binding region of the P450.
Conclusions
These are the first examples of potential function polymorphisms resulting from missense mutations in the CYP3A4 gene. The CYP3A4*2 allele was found to encode a P450 with substratedependent altered kinetics compared with the wild‐type P450.
Clinical Pharmacology & Therapeutics (2000) 67, 48–56; doi: 10.1067/mcp.2000.104391
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