Thick backed carbon targets via mechanical rolling

Greene, J. P.; Voss, P.; Starosta, K.

doi:10.1007/s10967-013-2673-x

Cited by 8 publications

(3 citation statements)

References 6 publications

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“…The experiment was split into two parts, with the first using a target consisting of a 433 µg/cm 2 carbon layer with a thick 28.79 mg/cm 2 gold backing in order to facilitate lifetime measurements of excited states in 28 Mg via the DSAM [24]. The second part used a selfsupporting thin target foil of 500 µg/cm 2 diamond-like carbon produced by Micromatter [25] separated from a gold catcher foil positioned 2 mm downstream from the target.…”

Section: Methodsmentioning

confidence: 99%

Structure of Mg28 and influence of the neutron pf shell

et al. 2019

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Gamma-ray spectroscopy and lifetime measurements using the Doppler Shift Attenuation Method (DSAM) were performed on the nucleus 28 Mg near the N = 20 'island of inversion', which was populated using a 12 C(18 O,2p) 28 Mg fusion-evaporation reaction to investigate the impact of shell evolution on its high-lying structure. Three new levels were identified at 7203(3), 7747(2), and 7929.3(12) keV along with several new gamma rays. A newly extracted B(E2; 4 + 1 → 2 + 1) of 42(7) e 2 fm 4 indicates reduced collectivity in the yrast band at high spin, consistent with ab initio SA-NCSM calculations. At high excitation energy, evidence for the population of intruder orbitals was obtained through identification of negative parity levels (I π = (0, 4) − , (4, 5) −). Calculations using the SDPF-MU interaction indicate that these levels arise from single neutron excitation to the pf shell and provides evidence for the lowering of these intruder orbitals approaching the 'island of inversion'.

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Section: Methodsmentioning

confidence: 99%

Structure of Mg28 and influence of the neutron pf shell

et al. 2019

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“…The state of interest was populated by Coulomb excitation of a 1.75 AMeV 36 Ar beam on a 0.43 mg/cm 2 (1.9 μm) carbon target evaporated onto a 22.2 mg/cm 2 (11.5 μm) gold backing [41]. The target was mounted at the center of the TIP scattering chamber, which was enclosed within 13 TIGRESS clover detectors at a radial distance of 14.5 cm from the target position in the optimized peak-to-total configuration [42].…”

Section: Experimental Methods and Resultsmentioning

confidence: 99%

Doppler-shift attenuation lifetime measurement of the Ar3621+ level

Voss¹,

Drake²,

Starosta³

et al. 2017

Phys. Rev. C

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At TRIUMF, the TIGRESS Integrated Plunger device and its suite of ancillary detector systems have been implemented for charged-particle tagging and light-ion identification in coincidence with γ -ray spectroscopy for Doppler-shift lifetime studies and low-energy Coulomb excitation measurements. As a test of the device, the lifetime of the first 2 + excited state in 36Ar was measured from the γ -ray line shape of the 2transition using the Doppler-shift attenuation technique following Coulomb excitation. The line-shape signatures, vital for precision lifetime measurements, were significantly improved by enhanced reaction-channel selectivity using a complementary approach of kinematic gating and digital rise-time discrimination of recoiling charged particles in a silicon PIN diode array. The lifetime was determined by comparisons between the data and simulated line shapes generated using our TIGRESS Coulomb excitation code as an input to the Lindhard method, which was then extended and included as a class in GEANT4. The model-independent lifetime result of 490 ± 50 fs corresponds to a reduced quadrupole transition strength of B(E2; 2

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“…TIGRESS surrounded the TIGRESS integrated plunger (TIP) [12] setup which consisted of a wall of 24 16 × 14 mm 2 , 2-mm thick CsI(Tl) detectors located 51.7 mm downstream of the target. The beam was impinged onto a 2.165-µm (0.5-mg/cm 2 ) thick amorphous carbon target, backed by a 14.917-µm (28.8-mg/cm 2 ) thick gold foil to stop the beam-like particles [13]. A beam intensity of approximately 100 ppA was maintained for 30 hours.…”

Section: Methodsmentioning

confidence: 99%

Lifetimes of low-lying excited states in $^{86}_{36}$Kr$_{50}$

Henderson,

Chester,

Ball

et al. 2018

Preprint

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Background: The evolution of nuclear magic numbers at extremes of isospin is a topic at the forefront of contemporary nuclear physics. N = 50 is a prime example, with increasing experimental data coming to light on potentially doubly-magic 100 Sn and 78 Ni at the proton-rich and protondeficient extremes, respectively.Purpose: Experimental discrepancies exist in the data for less exotic systems. In 86 Kr the B(E2; 2 + 1 → 0 + 1 ) value -a key indicator of shell evolution -has been experimentally determined by two different methodologies, with the results deviating by 3σ. Here, we report on a new highprecision measurement of this value, as well as the first measured lifetimes and hence transition strengths for the 2 + 2 and 3 − (2) states in the nucleus. Methods:The Doppler-shift attenuation method was implemented using the TIGRESS gammaray spectrometer and TIGRESS integrated plunger (TIP) device. High-statistics Monte-Carlo simulations were utilized to extract lifetimes in accordance with state-of-the-art methodologies.Results: Lifetimes of τ (2 + 1 ) = 336 ± 4(stat.) ± 20(sys.) fs, τ (2 + 2 ) = 263 ± 9(stat.) ± 19(sys.) fs and τ (3 − (2) ) = 73 ± 6(stat.) ± 32(sys.) fs were extracted. This yields a transition strength for the first-excited state of B(E2; 2 + 1 → 0 + ) = 259 ± 3(stat.) ± 16(sys.) e 2 fm 4 . Conclusions:The measured lifetime disagrees with the previous Doppler-shift attenuation method measurement by more than 3σ, while agreeing well with a previous value extracted from Coulomb excitation. The newly extracted B(E2; 2 + 1 → 0 + 1 ) value indicates a more sudden reduction in collectivity in the N = 50 isotones approaching Z = 40.

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Thick backed carbon targets via mechanical rolling

Cited by 8 publications

References 6 publications

Structure of Mg28 and influence of the neutron pf shell

Structure of Mg28 and influence of the neutron pf shell

Doppler-shift attenuation lifetime measurement of the Ar3621+ level

Lifetimes of low-lying excited states in $^{86}_{36}$Kr$_{50}$

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