How can I customize "weight_decay" in caffe0.15 via digits6.0

I would like to customize weight_decay in solver.prototxt.

solver.prototxt

test_iter: 300
test_interval: 901
base_lr: 0.01
display: 100
max_iter: 27030
lr_policy: “step”
gamma: 0.1
momentum: 0.9
weight_decay: 0.0001 <<----------------------How can I customize?
stepsize: 8920
snapshot: 901
snapshot_prefix: “snapshot”
solver_mode: CPU
net: “train_val.prototxt”
solver_type: SGD
iter_size: 1

Best Gegards