ABSTRACT
The nuclear two-photon or double-gamma (2γ) decay is a second-order electromagnetic process whereby a nucleus in an excited state emits two gamma rays simultaneously. To be able to directly measure the 2γ decay rate in the low-energy regime below the electron-positron pair-creation threshold, we combined the isochronous mode of a storage ring with Schottky resonant cavities. The newly developed technique can be applied to isomers with excitation energies down to â¼100 keV and half-lives as short as â¼10 ms. The half-life for the 2γ decay of the first-excited 0^{+} state in bare ^{72}Ge ions was determined to be 23.9(6) ms, which strongly deviates from expectations.
Subject(s)
Cervical Vertebrae/surgery , Cranial Nerve Neoplasms/surgery , Hypoglossal Nerve/surgery , Medulla Oblongata/surgery , Neurilemmoma/surgery , Spinal Neoplasms/surgery , Cervical Vertebrae/pathology , Cranial Nerve Neoplasms/diagnosis , Cranial Nerve Neoplasms/pathology , Follow-Up Studies , Humans , Hypoglossal Nerve/pathology , Magnetic Resonance Imaging , Male , Medulla Oblongata/pathology , Middle Aged , Neurilemmoma/diagnosis , Neurilemmoma/pathology , Neurologic Examination , Reoperation , Spinal Neoplasms/diagnosis , Spinal Neoplasms/pathology , Tomography, X-Ray ComputedABSTRACT
The purpose of this paper is to analyse surgical aspects of aneurysms of the distal extracranial internal carotid artery. Nine cases of extracranial carotid artery aneurysm are reported. Five were fusiform, located at the carotid bifurcation, and four were saccular, confined to the internal carotid artery. An end-to-end plication technique and Dacron patch angioplasty were employed for all fusiform aneurysms. In three saccular lesions, resection and 4-mm polytetrafluoroethylene (PTFE) graft interposition were carried out. In one case with a high lesion, ligation of the carotid artery was performed. Ligation resulted in severe postoperative stroke and fatal outcome. One patient with a saccular lesion developed a transient ischaemic attack after the operation. In other patients no central neurological deficit was produced by the surgery itself. Transient cranial nerve damage occurred in four patients (two hypoglossal nerve: two superior laryngeal nerve). As demonstrated by these cases, synthetic material may be used in restoration of the carotid artery. It is concluded that, according to type, location of the aneurysm and adequacy of contralateral cerebral blood flow, selective management is necessary.
