Final answer:
In Randall Jarrell's poem, the 'new womb' the speaker is referring to is the ball turret, which is a metaphorical expression contrasting the life-giving quality of a womb with the deadly role of the ball turret gunner in World War II.
Step-by-step explanation:
In the poem "Death of a Ball Turret Gunner" by Randall Jarrell, the new womb that the speaker finds himself in is the ball turret. The ball turret was a spherical, cramped compartment used in World War II bombers, wherein a gunner would be positioned to defend the aircraft against enemy fighter planes. The term "womb" is metaphorical, used to express the close, enclosing nature of the ball turret, and contrasts the birth and life connotations of a womb with the deathly occupation of the gunner inside the turret.