Proton halos in exotic light nuclei

The current study on proton halos in exotic light nuclei is reviewed and discussed. We place emphasis on the newly discovered proton halo in 23Al. A measurement of the reaction cross section of N=10 isotones and Z=13 isotopes is performed at Lanzhou in China. An abnormal increase in the reaction cross section is observed for 23Al. This abnormal increase, combined with other data, strongly suggests that there is a proton halo in 23Al. The possible cause for a proton halo in 23Al is analyzed, and it is found that deformation can be important for it. Other candidates for proton halos are predicted.