SEARCH FOR MAGNETIC MONOPOLES TRAPPED IN OLD IRON-ORES USING A SUPERCONDUCTING DETECTOR
SEARCH FOR MAGNETIC MONOPOLES TRAPPED IN OLD IRON-ORES USING A SUPERCONDUCTING DETECTOR
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DOI：
10.1103/physrevd.36.3359
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发表时间：
1987-12-01
影响因子：
5
通讯作者：
WATANABE, T
中科院分区：
文献类型：
--
作者：
EBISU, T;WATANABE, T
利用一组两个超导量子干涉装置（SQUID）通量计在铁矿石中寻找磁捕获单极子。我们在一个工业选矿厂的烧结炉下运行了两个月，试图观察单极子从经热处理顺磁的矿石中释放出来后穿透超导线圈的信号。没有发现与大于0.6倍狄拉克单位强度g d的磁荷通过相一致的候选事件。所检查的矿石的总重量在137到~ 104吨之间变化，这取决于假设的单极子释放机制。通过最保守的估计，我们获得了铁矿石中超大质量单极子（10 14-10 17 GeV/c 2）密度的上限为2.2× 10−7单极子/g[95%置信水平（CL）]，其中涉及年龄为10 7 - 10 9年的铁/铁-铁磁性成分，其密度为10%。自由单极子通量也小于1.4× 10−10/ cm2 sr (90% CL)，无论其质量或速度如何，从两个20 cm-直径的搜索线圈中获得57 d的寿命。
Magnetically trapped monopoles were sought in iron ores using a set of two SQUID (superconducting quantum-interference device) fluxmeters. We operated the apparatus under a sintering furnace in an industrial ore-processing plant for two months and tried to observe a signal of a monopole penetrating superconducting coils after its release from ore paramagnetized through a heat treatment. No candidate events were found consistent with the passage of a magnetic charge greater than 0.6 times Dirac’s unit strength g D. The total weight of ore examined varies between 137 and∼ 10 4 tons, depending on what mechanism is assumed for the release of monopoles. By taking the most modest estimate, we obtain an upper limit of 2.2× 10− 7 monopoles/g [95% confidence level (CL)] for the density of very massive monopoles (10 14–10 17 GeV/c 2) in iron ores which involve ferro/ferri-ferrimagnetic ingredients of age 10 7–10 9 yr to the extent of 10%. The free-monopole flux is also obtained as less than 1.4× 10− 10/cm 2 sec sr (90% CL), irrespective of its mass or velocity from a 57-d live time of two 20-cm-diam search coils.