The TAROGE-M radio observatory is a self-triggered antenna array on top of the ∼2700 m high Mt. Melbourne in Antarctica, designed to detect impulsive geomagnetic emission from extensive air showers induced by ultra-high energy (UHE) particles beyond 1017 eV, including cosmic rays, Earth-skimming tau neutrinos, and particularly, the “ANITA anomalous events” (AAE) from near and below the horizon. The six AAE discovered by the ANITA experiment have signal features similar to tau neutrinos but that hypothesis is in tension either with the interaction length predicted by Standard Model or with the flux limits set by other experiments. Their origin remains uncertain, requiring more experimental inputs for clarification. The detection concept of TAROGE-M takes advantage of a high altitude with synoptic view toward the horizon as an efficient signal collector, and the radio quietness as well as strong and near vertical geomagnetic field in Antarctica, enhancing the relative radio signal strength. This approach has a low energy threshold, high duty cycle, and is easy to extend for quickly enlarging statistics. Here we report experimental results from the first TAROGE-M station deployed in January 2020, corresponding to approximately one month of livetime. The station consists of six receiving antennas operating at 180–450 MHz, and can reconstruct source directions of impulsive events with an angular resolution of ∼0.3°, calibrated in situ with a drone-borne pulser system. To demonstrate TAROGE-M's ability to detect UHE air showers, a search for cosmic ray signals in 25.3-days of data together with the detection simulation were conducted, resulting in seven identified candidates. The detected events have a mean reconstructed energy of 0.95-0.31 +0.46 EeV and zenith angles ranging from 25° to 82°, with both distributions agreeing with the simulations, indicating an energy threshold at about 0.3 EeV. The estimated cosmic ray flux at that energy is 1.2-0.9 +0.7 × 10-16 eV-1 km-2 yr-1 sr-1, also consistent with results of other experiments. The TAROGE-M sensitivity to AAEs is approximated by the tau neutrino exposure with simulations, which suggests comparable sensitivity as ANITA's at around 1 EeV energy with a few station-years of operation. These first results verified the station design and performance in a polar and high-altitude environment, and are promising for further discovery of tau neutrinos and AAEs after an extension in the near future.
Fast Radio Bursts (FRBs), bright millisecond-duration radio transients are happening thousands of times per day. FRBs' astrophysical mechanisms are still puzzling. Bustling Universe Radio Survey Telescope for Taiwan (BURSTT) is optimized to discover and localize a large sample of bright and nearby FRBs. BURSTT will have a large field-of-view (FoV) of ∼10 4 deg 2 for monitoring the whole visible sky all the time, a 400 MHz effective bandwidth between 300-800 MHz, and the sub-arcsecond localization capability with several outrigger stations hundreds to thousands of km away. Initially, BURSTT will equip with 256 antennas, which we will test different designs and improve the system performance. Through the scalable features, BURSTT could equip with more antennas and eventually optimized designs. We expect that BURSTT initially would detect and localize ∼100 bright (≥100 Jy ms) and nearby FRBs per year to sub-arcsecond precision. Besides, the large FoV yields monitoring FRBs with high cadence, which is crucial to understanding the repetition of FRBs. Multi-
Hypersplenism and thrombocytopenia are common complications of liver cirrhosis or thalassemia, but current treatment strategies are limited. This study aimed to evaluate the efficacy and safety of thalidomide in the treatment of hypersplenism and thrombocytopenia in patients with liver cirrhosis or thalassemia. A total of 31 patients with hepatic cirrhosis (n=19) or thalassemia (n=12) diagnosed with hypersplenism and thrombocytopenia (platelet count [PLT] <100×10 9 /L) were included in this prospective cohort study between January 2015 and May 2017. Patients were treated with thalidomide (150–200 mg/d) plus conventional therapy. Spleen length, PLT, leukocyte count (WBC), absolute neutrophil count (ANC), and hemoglobin level (Hb) were measured at baseline, 3, 6, and 12 months. Any adverse events were noted. All of the 31 patients were showed a progressive increase PLT during the 12-month follow-up, and similar results were obtained when subgroup analyses were performed based on the primary disease (cirrhosis or thalassemia). WBC, ANC, and Hb also increased progressively during the 12-month follow-up. Spleen length decreased progressively during the follow-up. No serious adverse events occurred. Thalidomide is a potential treatment for thrombocytopenia caused by hypersplenism in patients with cirrhosis or thalassemia.
TAROGE experiment and reconstruction technique for near-horizon impulsive radio signals induced by Ultra-high energy cosmic raysYaocheng Chen * on behalf of the TAROGE Collaboration
We present a portable calibration pulser system applied to radio antennas in order to detect ultrahigh energy cosmic rays and neutrinos. The system consists of a solid-state high-voltage impulse generator, a digital attenuator, a wide band (150-350 MHz) bi-cone antenna, and a differential GPS. Taking an advantage of light weight of each component (less than 1.4 kg), we developed an airborne calibration system by attaching them on a commercial drone. This system will be used for TAROGE experiment in high mountains as well as in Antarctica. We will report on its design, construction, performance, and potential applications for future radio experiments.
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