  Hyperpolarization of nuclear spins enhances nuclear magnetic resonance
signals, which play a key role for imaging and spectroscopy in the natural and
life sciences. This signal amplification unlocks previously inaccessible
techniques, such as metabolic imaging of cancer cells. In this work, electron
spins from the photoexcited triplet state of pentacene-doped naphthalene
crystals are used to polarize surrounding protons. As existing strategies are
rendered less effective by experimental constraints, they are replaced with
optimal control pulses designed with RedCRAB. In contrast to previous optimal
control approaches, which consider an average single nucleus, this closed-loop
optimization is macroscopic. A 28% improvement in signal and 15% faster
polarization rate is observed. Additionally, a strategy called
Autonomously-optimized Repeated Linear Sweep (ARISE) is introduced to
efficiently tailor existing hyperpolarization sequences in the presence of
experimental uncertainty to enhance their performance. ARISE is expected to be
broadly applicable in many experimental settings.
