RESUMO
High-power lasers that fit into a university-scale laboratory can now reach focused intensities of more than 10(19) W cm(-2) at high repetition rates. Such lasers are capable of producing beams of energetic electrons, protons and gamma-rays. Relativistic electrons are generated through the breaking of large-amplitude relativistic plasma waves created in the wake of the laser pulse as it propagates through a plasma, or through a direct interaction between the laser field and the electrons in the plasma. However, the electron beams produced from previous laser-plasma experiments have a large energy spread, limiting their use for potential applications. Here we report high-resolution energy measurements of the electron beams produced from intense laser-plasma interactions, showing that--under particular plasma conditions--it is possible to generate beams of relativistic electrons with low divergence and a small energy spread (less than three per cent). The monoenergetic features were observed in the electron energy spectrum for plasma densities just above a threshold required for breaking of the plasma wave. These features were observed consistently in the electron spectrum, although the energy of the beam was observed to vary from shot to shot. If the issue of energy reproducibility can be addressed, it should be possible to generate ultrashort monoenergetic electron bunches of tunable energy, holding great promise for the future development of 'table-top' particle accelerators.
RESUMO
Thyroglossal duct carcinoma is rare, and its presentation is similar to that of a thyroglossal duct cyst: a nontender, palpable mass in the midline location. Rapid increase in growth may be a sign of malignancy, but the diagnosis is based on the pathology of the cyst. Initial treatment of thyroglossal duct carcinoma is the same surgical procedure used for removal of a thyroglossal duct cyst. Further surgery depends on the finding of thyroid nodules or positive lymph nodes but is rarely necessary. The recurrence rate after simple excision is low. Postoperative radioiodine ablation or radiation is considered in cases of recurrence or metastasis. In this report, we describe a patient with a new-onset, nontender, neck mass who had a Sistrunk procedure for a presumed thyroglossal duct cyst and was found to have papillary carcinoma.
