Diffusion of quantum liquids in bulk and

confinement:

A neutron scattering investigation

Scott Hanna

Supervisors: Timothy Prisk, Richard Azuah
● Refinement of last years experiment: Diffusion of bulk 

liquid normal H2

● Dynamics of confined liquid hydrogen deuteride

● Applications of research to high school physics

Outline of presentation
Why H2 and HD?

● They form a quantum fluid and 

solid in nature

● They can be modeled from first 

principles

● H2 vs. HD - spin properties

https://hub.wsu.edu/ise/design/vortex-tube/
Motivation for the study of liquid H2 diffusion

● Large zero-point energy 

contribution

● Better statistics at lower 

resolution will refine our 

results

● A smaller counting time will 

allow more temperature 

measurements.
Neutron Scattering and Diffusive Dynamics of Low

Temperature Hydrogen

Lorentzian Structure Factor

Jump Diffusion Width Model
Sample Environment

● Annular radius around 0.1mm for 

10% scattering.

● We collected data for 8 different 

temperatures between 14.5 K 

and 20.5 K.

● We also performed 

measurements of the empty can 

background, and vanadium 

resolution.
Resolution: ~60

Temperatures between 

14.5 K and 20.5 K.

Our instrument: The disk chopper spectrometer (DCS)

Diffusive time scales: 

 ~ s
Modeling quasielastic broadening

Modeling Temperature Dependence and Conclusion

● Our results provide 

independent experimental 

confirmation

● Quantitative Agreement:

Activation Energy

Qexp = 3.864 +/- 0.118 meV

Qlit = 3.85941 meV [1]
Motivation for studying the dynamics of confined HD

● Effects of confinement

○ Increase of liquid viscosity

○ Suppression of freezing temperature. Supercooling.

● Why HD and not H2?

○ Adsorption dependence on ortho H2 content

○ H2 ortho to para conversion
Sample Characterization

MCM-41 Powder - SiO2 Hexagonal Pore 

Structure

Pore Size: ~3-5nm

Our interest is in the full pore phase

Thank you Taner!

Fodor et.al., Microporous and Mesoporous Materials 56, 101-109 (2002)
Experiment Details

● Preparation of MCM-41

● Sample Can

○ ~1mm annular radius for 10% scattering.

● DCS settings

○ Medium resolution, λ = 4.8 Å

● Measured confined HD at five different 

temperatures:

○ 14.5K to 20.5K which consist of temperatures 

below and above the triple point of HD (16.6K).

● Measured bulk HD at the same DCS 

settings but in the 0.1 mm annular can.

Bulk and Confined HD: Cut at Q=0.56 Å^-1
Further Analysis

● Determine a diffusive model of liquid HD in confinement.

Future Study

● At what lowest temperature do we continue to see quasi-elastic broadening?

● Perform the experiment for p-H2. Theoretical models suggests p-H2 

superfluidity at ~6K [1].

● Quantify pore-size influence on the suppression of freezing temperature.

η is the dynamic

viscosity
What did I learn and experience?

● Continuing work on an 

ongoing project

● Taking part in the summer 

school

● Science is hard work

● Constant reassessment 

and refinement.

Atlas Collaboration, “Observation of a new particle in the search for the 

Standard Model Higgs boson with the ATLAS detector at the LHC”
Last year: Inquiry based experimentation

Pose an inquiry question with a selection of 

hypothetical theoretical explanations.

Students formulate their own experimental 

methodology

● Choose independent variable and controls

● Choose materials and measuring devices

Experimental uncertainties

Presentation of results and inferences.
Results from implementation

● Managed to convert 5 major labs

● Students dove right in.

● “But my R^2 value is close to 1”

● Common issues in student reports:

○ Lack of detail on sources of error, 

environmental factors.

○ Lack of referencing results in 

formulation of conclusion.

● Assessing reports was a lot of work on 

my part.
Expanding on inquiry based research

Who is the arbiter of validity?

Q: How can we make the process of writing and getting feedback on a 

research paper more realistic and at the same time give students experience 

interpreting research papers?

A: Implement a peer review process.
Research Review Criteria

Soundness of Design:

● Is the work technically correct?

● Is the data reliable? What 

environmental factors did they fail 

to account for?

● Does the data support their 

conclusion? Is there a logical flow 

to their reasoning?

Quality of writing:

● Can you follow the experimental 

design?

● Are the figures clear and do they 

support their findings?

● Are the calculations clear and 

correct?
Thank You!

Experiment Supervisors: Timothy Prisk and Richard 

Azuah

Yamali Hernandez, Dan Neumann, Rob Dimeo

Antonio Faraone, Michihiro Nagao, Elizabeth Kelley, 

Madhu Tyagi

Juscelino Leao, Yegor Vekhov, Tanya Dax, Yiming 

Qiu, Taner Yildirim

Nick Butch, Wei Zhou, Craig Brown
Questions?