# Beamtime hacks

## Tips for designing an optimal measurement plan
Below are a list of considerations.  It's non-exhaustive.  As development work is ongoing, some of these considerations may be outdated.  Consult with your local contact.

- Multi-hour, automated overnight measurements with the beamline may be infeasible, due to heat-induced deformation of the M1 mirror (need to periodically re-tune M1 pitch, etc.).  The measurements could be semi-automated, if a user periodically stops by the hutch.
- Unless the surface is ultra-clean, chemical mapping with XAS-PEEM is preferred to XPEEM, as the yield of secondary electrons is expected to be higher versus primary photoelectrons
- The continuous application of a high voltage between the microscope objective and sample surface generally leads to carbon deposition - periodic surface regeneration may be needed
- Scangui (ascan macro) enables most beamline and microscope parameters to be swept --> automated scans
- Five slots exist in the storage chamber attached to the main chamber, though 2-4 slots are typically occupied.  Talk to your local contact about storing sample(s) inside.
- Micro-ARPES typically works well with photon energies up to ~100 eV.  The photon flux decreases above 100 eV for the 1200 lines/mm grating, plus the photoionization cross-sections decrease with increasing photon energy.
- The beamline elements are contaminated with carbon, yielding lower-than-expected photon flux at energies at and near the carbon K-edge
- The beamline lacks proper i0-type normalization, needed for generating high-quality X-ray absorption spectra.  A gold mesh exists upstream of the M4 mirror, but the mesh is dirty and we cannot deposit fresh gold onto it.
- When XAS measurements are desired, check the literature (and/or use Google Image search) to determine if the edge has been measured before - *having a core level doesn't mean you have an absorption edge*

## Tips for operating the beamline

- Track the beamline flux by periodically inserting the photodiode into the beam path; tuning the pitch of the M1 mirror is usually sufficient to maximize the flux.
- The spot size at the sample position is around 15 um (H) x 15 um (V) with a 0.15 mm exit slit opening in the vertical and horizontal directions (the image at the exit slit is demagnified by a factor of 10 at the sample position).
- Peak photon flux is obtained at ~100 eV (for the 1200 lines/mm and 300 lines/mm gratings)

## Toilets and water/tea/coffee stations

Tea, coffee, hot chocolate, etc. are available for free, 24/7.  The approximate locations of the drink stations and toilets are displayed in the schematic layout of the Lab.

```{image} ./imgs/lab_schematic_toilets_water.png
:align: center
:width: 700
```

Figure 1. Schematic of MAX IV, showing the toilets and drink stations that are easily accessible from MAXPEEM.


## WiFi

- maxiv_user (log in with MAX IV DUO username and password)
- maxiv_visitors (intended for 1 day users, Internet access only, receive a token through your email address)
- eduroam (Internet access only)
- maxiv_staff (not applicable to users)

For more details on access privileges, etc. see <https://www.maxiv.lu.se/beamlines-accelerators/controls-it/it-services/wifi/>


## Food options

In short, the main options are:
\* visiting food trucks (usually located close to the main entrance, where the reception is, from 11-13 Monday - Friday); call Reception (+46462229872) for the latest schedule.
\* cooking in the user kitchen at MAX IV and/or in the guestrooms at Forskarhotellet
\* microwaving frozen food purchased from the vending machines
\* ordering food delivery (e.g. foodora.se)
\* stationary food truck "Dagens lunch 60" serving burgers and daily specials (5 minute talk from the Lab, Odarslövsvägen 50)

See <https://blochdocs.maxiv.lu.se/food.html> for more details.


## Resting and exercise rooms

A sleeping room is available in the basement of the E-building.  First come, first served.  An exercise room, equipped with a pull-up bar, bench, weights and cardio training machines, is also available in the basement.


## Tools and supplies available in the MAXPEEM prep lab

- Hand tools: tweezers, pliers, screwdrivers, wrenches, etc.
- Vacuum parts
- Kapton tape
- Dessicator
- Optical microscope

EPO-TEK epoxies, pastes, etc. stored in the D3 chemical lab (fridge).  **Ask if you need something special.**