The Alvarez team built chambers of 1.5 in , 2.5 in , 4 in , 10 in , and 15 in using liquid hydrogen , and constructed of metal with glass windows .
The tracks could be photographed .
The Alvarez team built chambers of 1.5 in , 2.5 in , 4 in , 10 in , and 15 in using liquid hydrogen , and constructed of metal with glass windows , so that the tracks could be photographed .