Given the following context:

The term "Gadget" was a laboratory euphemism for a bomb, from which the laboratory's weapon physics division, "G Division", took its name in August 1944. At that time it did not refer specifically to the Trinity Test device as it had yet to be developed, but once it was, it became the laboratory code name. The Trinity Gadget was officially a Y-1561 device, as was the Fat Man used a few weeks later in the bombing of Nagasaki. The two were very similar, with only minor differences, the most obvious being the absence of fuzing and the external ballistic casing. The bombs were still under development, and small changes continued to be made to the Fat Man design.To keep the design as simple as possible, a near solid spherical core was chosen rather than a hollow one, although calculations showed that a hollow core would be more efficient in its use of plutonium. The core was compressed to prompt super-criticality by the implosion generated by the high explosive lens. This design became known as a "Christy Core" or "Christy pit" after physicist Robert F. Christy, who made the solid pit design a reality after it was initially proposed by Edward Teller. Along with the pit, the whole physics package was also informally nicknamed "Christy['s] Gadget".Of the several allotropes of plutonium, the metallurgists preferred the malleable δ phase. This was stabilized at room temperature by alloying it with gallium. Two equal hemispheres of plutonium-gallium alloy were plated with silver, and designated by serial numbers HS-1 and HS-2. The 6.19-kilogram (13.6 lb) radioactive core generated 15 W of heat, which warmed it up to about 100 to 110 °F (38 to 43 °C), and the silver plating developed blisters that had to be filed down and covered with gold foil; later cores were plated with nickel instead. The Trinity core consisted of just these two hemispheres. Later cores also included a ring with a triangular cross-section to prevent jets forming in the gap between them.

answer the following question:

What is the code name of the device that was developed after it had a code name? 

Gadget