@article{article, title  = {{Ballistic Focusing of Polyenergetic Protons Driven by Petawatt Laser Pulses}},

 publisher = {{American Physical Society (APS)}},

 url = {{}},

 year = {{2011}},

 month = {{6}},

 author = {{Kar S and Markey K and Borghesi M and Carroll DC and McKenna P and Neely D and Quinn MN and Zepf M}},

 doi = {{10.1103/physrevlett.106.225003}},

 volume = {{106}},

 journal = {{Physical Review Letters}},

 issue = {{22}},

 note = {{Accessed on 2024/10/23}}}