A US team examined Trinitite, the glassy ground debris from the first-ever nuclear test that the US Army conducted in 1945 in New Mexico.
They used advanced analytical techniques to reveal details about the materials used to construct the bomb.
The study appears in the journal PNAS.
The first atomic bomb exploded in the early hours of 16 July, 1945, in the desert near Alamogordo Air Base. Code-named "Trinity", the detonation was just a test conducted far away from any settlements.
When two atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki just weeks later, in the final stages of the World War II, thousands perished in a glimpse.
As many as 90,000-166,000 people died in Hiroshima and some 60,000-80,000 in Nagasaki. About half of the deaths happened on the day of the bombing.
Tracing the responsible
Now, many consider the threat of a nuclear attack by terrorists to be very real. Such an attack could potentially wipe out whole cities.
But if someone does ever undertake such an attack, could the culprits behind the bomb ever be found?
The current study's lead author Albert Fahey, of the National Institute of Standards and Technology (Nist) in Gaithersburg, US, seems to think so.
"Prior to this, pretty much everyone assumed that everything would be vaporised, it would all be homogeneous and we would have no idea whatsoever where this thing came from," he told BBC News.
"Turns out that's not true."
