Perhaps you could present some actual data to support your argument??
I should apologize at first. I forgot to say thank You a lot for this extensive excellent measurements and data. I wish I could had this at hand 6 years ago and could show that under nose of our management, so they would not cheapskate on air conditioning (AC) system in our lab.
I am not questioning credibility of data, I am questioning only the proposed mechanism for observed bias drifts.
So lets look to my claims step by step.
I have no humidity logs in our lab, albeit there is plan for those. The hardware is sitting and waiting for configuration, but I had no time to configure it. I have at the moment only extensive temperature data (logged every 1 minute for a bit more than a year with some brakes) from different places such as outside wall near window (old site for AC control panel (and internal thermometer used for T control), inner build wall where P10 gas bottle is presently placed by (also a new site for AC control panel), P-10 bottle metal case, backside of EPMA (air at 20 cm from floor, 10 cm from microprobe), microprobe chasis at two points (column isolation valve screw (EP6), junction of second ion pump and column).
Initial idea for thermometer network came from some weird behavior of one of spectrometers, so I wanted to see if air streams from AC are not effecting more one of the spectrometers (the one with weird behavior) and so wanted to measure separate temperatures for every spectrometer (using DS18B20, digital 1-wire thermometers connected in network). Before I started long term logging I had re-modified the network to troubleshoot vacuum leak problems (I was suspecting either metal gasket of that valve or metal gasket of second ion pump, thus the weird positions given below). Also I had expanded that network with other points in lab to prove that AC control panel was initially badly placed, and P10 Gas bottle had to be moved from external wall to internal wall (I was getting critique from management for moving stuff, and needed hard proof). After P10 gas movement we saw a lot of improvement in calibration stability, but that was not enough. Unfortunately I started logging temperatures with that network only after AC and P10 Gas placement modifications, so I can't compare directly with old setup. You can see in above picture that at winter the temperature of outer wall gets much cooler, and gas bottle (when it was standing by outer wall) was also surely affected. Also AC logic within c/p in old place was often getting very biased temperature readings. I.e. in cold winters we were getting very warm room (i.e. when -20 C outside), while I have no data record from those times, it was very obvious for human senses.
I should mention that our AC panel is set to keep in between 23 (start cooling if above) and 22 (heat up if below) degrees, and integrated thermometer reading on AC c/p is showing 22 or 23 whole year. I also should mention that previously we had in room installed some USB temperature humidity logger which was also showing very stable temperatures (Multimetrix DL 53), basically lulling us into believing that there is no issues. That useless piece of USB logger was installed by Cameca with our new probe. The "PRO" thermometers/loggers have one significant drawback - they are encased in plastic packaging and measure highly averaged temperature - they measure something from alternative reality - or like going to listen for opera but putting the bucket on the head. That is why I made network of thermometer chips (DS18B20) which are bare-exposed to the stuff which it is supposed to measure (i.e. direct contact to gas bottle with thermal paste in between chip and bottle, but well isolated from direct air blow; or other example - directly exposed/hanged in the air for air temperature measurement - so that room humidity and air streams would affect the thermometer in exactly same manner as the machine). Before assembling the network of thermometers I had tested them all by simultaneously measuring temperatures while keeping them immersed in same liquid container to see that they get exactly same (+/- 0.0625 C) temperatures in range of 30-15 degrees. So the temperature differences showed in charts are not artificial but real. DS18B20 is able to differentiate temperatures with 0.0625 C steps, which is pretty good and it is able to capture not only daily and seasonal temperature fluctuations but also individual AC cooling/heating cycles. (In the end this precision helped me to locate and fix vacuum leak).
The temperatures are pretty stable during autumn, winter and spring. As an example 4 days during stable period:
However it is pretty terrible during hot summer days:
Here comes so waited autumn, which begins the stable cycle again (the figure below depicts logged temperatures with transition from hot summer weather changed with atmospheric front going through location and lowering outside temperatures):
This I think summarizes currently gathered all temperature measurements:
So why during summer our lab gets so bad variations? I think (I still need to install humidity measurements hardware to be 100% sure) that it is so at summer as lab is coolest place compared to the surrounding rooms and halls in the building and gathers/traps humidity, that is outside from lab (inside building) and outside of building temperatures gets significantly higher during hot day than inside the lab. The increased humidity significantly increases the rate of feedback between air conditioning injected cold air streams and AC c/p (where we can see very steep negative peaks recorded on all temperature readings). As control panel logic recognizes that AC is over-cooling it switches off AC very rapidly and waits for threshold to be crossed again. Thus there is much larger cycles than during stable period, where AC works in PID mode (like i.e. water chiller; it is integrating temperature measurement and controlling AC air stream strength and temperature not so violently - thus on chart we see smaller cycles which switches much more often). And so these are the data which I base my question about if being sure that room temperature is rock stable, and being sure about all heat fluxes.
Talking about P10 gas temperature and its influence to counting, I have rather "anecdotal" experience without real measurements (sorry, no data). When we change P10 gas, old calibrations gets instantly outdated; But then after some time the newly made calibrations gets outdated, and old calibrations gets again to be good. The effect is clearly correlative with temperature differences between lab room, that is: if weather is mild (spring or autumn) and temperature of transported bottle is similar to our lab, then there is no or very week calibration misalignment observed. But if gas bottle is transported and changed at cold winter or hot summer, we get 1-2 weeks of constantly out-dating calibrations until gas temperature stabilizes with room temperature. Then we can use again old calibrations. I know that gas bottles are stored in some not-heated or cooled shed by gas producer, and so its temperature equilibrates with environment/weather before being transported to our lab.
Now talking about electronics, most of datasheets of electronic components present in one or other form how the values of described component react to temperature changes and (optionally) humidity. Resistors are particularly sensitive to temperature and so rating can change (and so voltage values, i.e. which are fed into ADC, or other way around - the digital values which are converted from digital to analog and amplified (there are always some resistors in control loops of OPAMPs in most cases)). I don't think I can give any data for that.