This page contains the minutes from all DarkLight meetings, with most recent meetings at the top.

Please feel free to add details if they are missing, and to add links to materials where possible.

6/27/22 - General Meeting: https://indico.mit.edu/event/507/

1. Beginning the meeting with discussion about the wiki location.
   1. Doug does not like the UX of the Github wiki, but the MIT wiki requires an MIT account to access
   2. Ross volunteers to look into smoothly integrating images into the GitHub wiki
2. Doug
   1. Raises discussion of the milestones made by Richard
      1. Have a technical design of the experiment by August, implemented in Overleaf
      2. How should we organize who writes what? Roughly aim to have the proposed institutional responsibilities guide the drafting
      3. Doug will implement a draft, and move the existing TDR report into a new Overleaf repo
   2. Some kind of holiday next Monday, so we will cancel the meeting
3. Ross
   1. Workshop
      1. Sent around draft call for proceedings to workshop organizers and it was approved, so now formally being sent to speakers
      2. Due August 1, as all Moore foundation money must be spent in the very early fall. Any delay jeopardizes being able to pay for late articles to be published
      3. Some discussion regarding hard and soft deadlines
      4. Likely will be fully published by mid-September
4. Kate
   1. Overview of the simulation meeting
      1. Dean has set up MainzGen code and showed some plots indicating reasonable output of the generator
      2. In some cases coordinate systems are confusing
5. Doug
   1. Had the first magnet meeting
      1. Didn’t get Harald, but had others
      2. Ernie is going ahead with Harald’s design, but with minor changes
      3. Aveen asked Harald to change pole shapes to be spherical, which better integrates into EPICS and design models
      4. Jan is concerned about space constraints
6. Aveen
   1. Other users are present at ARIEL, so spending time in control room
   2. DarkLight beam tests are currently scheduled for later July or early August
7. Doug
   1. Thinking about going through the beam time authorization procedure for TRIUM to get on site for tests
8. Jan
   1. DNP
      1. We should have an abstract submitted. Just one talk, not sure who will give it now, but will have several authors to choose later
      2. There is a CEU as well so we should send undergrads
9. Michael Kohl
   1. Working with JLab to find a way to set up the detector in such a way that it is externally accessible
10. Mike Hasinoff
    1. Getting a 600-800 ps timing resolution with existing scintillator
    2. New scintillator ordered and will test shortly with Mainz board
    3. Prepping for exam
    4. Same scintillator as MUSE, so should have same signal rise time, likely board is not fast enough

June 16, 2022 - General Meeting: https://indico.mit.edu/event/446/

1. Doug created an agenda for the meeting, but have a lack of attached presentations
2. Ross is still working on payment mechanisms at SBU for the workshop. Has identified a single person to approve the process
   1. IOP has set up a link to submit conference proceedings
   2. IOP require independent referee for proceedings, need someone outside of Darklight
   3. Do we have a nominee for referee?
   4. It is suggested we reach outside of SBU for a referee
   5. Jan suggests a few names at MIT
   6. Ross suggests someone at TRIUMF, maybe not on ARIEL
   7. Maybe Rouven Essig? Knows Dark Matter from electron scattering
   8. Ethan brought up the DarkLight proceedings and suggested adding everyone’s name to the proceeding as it is the first publication for this iteration of DarkLight. General agreement from the attendees.
3. Kate brings up timing of simulation meeting.
   1. We agree to move to weekly rather than biweekly for simulation meeting
   2. For new folks we are at a point where we understand the tools
   3. Working on creating a limit plot using existing simulation tools
   4. Jan has an additional student named Austin Colon who will be joining over the summer
   5. Request for Ethan to add Slack invite link to minutes
      1. https://join.slack.com/t/darklight-hq/shared_invite/zt-1ay7gkc4z-owCq7QpadFyVWVW70u1lkQ
4. Magnet discussion
   1. Ernie is on vacation
   2. Harald is not present but Jan will speak to him in person tomorrow
   3. Aveen wants a map of the field lines with some measurements
   4. Harald slides are almost sufficient but missing a little bit of detail
   5. Ross wonders if anyone from TRIUMF has had a chance to look at the magnet designs
      1. Aveen mentions Rick Bartman looked briefly and thought it looks reasonable. No obvious blocks for this design. Rick is head of beam physics department
5. Aveen mentions cryomodules are cooled down and planning some tests.
   1. DarkLight tests planned in July
   2. Does TRIUMF need extra hands for tests?
      1. Aveen does not think so
   3. Need people more for the test experiment next spring
6. Michael says SSP module has been unpacked and equipped with optical transceivers in LERF lab. Has online zero suppression to alleviate VME readout of GEMS
   1. GEMs could produce GB/s of data given how large they are. Zero suppression could reduce by factor of 5 to 10
   2. Have FPGA based real time assessment of clusters and fired strips
   3. Same as SBS program at JLab
   4. Just starting commissioning, leak tests, etc.
7. Kate has been working on trigger detectors. Using Alpha-G system.
   1. Not getting optimal timing. Working on offline corrections.
   2. Currently at 1 ns resolution
   3. Want to replicate Alpha-G performance before continuing
   4. They measure the time resolution using cosmic rays and time difference from double ended readout. 15 cm long paddles, path length variation could be a non-trivial effect on resolution
   5. Not using MAGIX board yet
   6. System does also record pulse height. Attempted to correct for walk effect
   7. Built in amplification is too big for signals, things get clipped at the maximum
8. Jan had a student who was interested in hardware, but is gone for the summer
   1. Ross and Jan want to revisit the hardware at SBU when Jan returns
9. SNOWMASS discussion with Richard
   1. Whole process was paused by COVID, but is restarting
   2. Richard is a co-convener for accelerator BSM and precision physics searches
   3. Richard can ensure DarkLight is mentioned in the document
   4. Can include two page Letter of Interest into SNOWMASS if people are interested
   5. Good to do in conjunction with conference proceedings
10. Doodle poll for next meeting
    1. No time works for everyone
    2. Monday 1-2 PM Eastern time is best, but missing Harald and Ernie
    3. Thursday afternoon might be good, but miss some TRIUMF people
       1. Some schedules restricted by teaching responsibilities which change soon
    4. Maybe we schedule a magnet design meeting and have them report back to group meeting
    5. Likely will need to schedule a second doodle poll when semester starts
    6. Moving to Monday at 1-2 PM Eastern time, but we will skip June 20th given short time scale
11. Doug will set up a magnet meeting
12. Doug set up another wiki to upload images
    1. Hosted on MIT wikis
13. Jan and Ross will show how to upload images to GitHub

June 9, 2022 - General Meeting: https://indico.mit.edu/event/425/

• Discussed restarting the minutes. We will rotate responsibilities monthly, per vote of the attending folks. SBU will have the remainder of the month of June. Then it will move to MIT (and they can nominate the next victim, for now. We should move to something more formal afterward).
• Yesterday, Richard led a discussion of the white paper we would like to add as a preface to the proceedings. Ross reports they will extend the paper lengths to 10 pages.
•  Ross will post Richard's slides from the editors meeting yesterday.
• Jan has added the OLYMPUS generator to the suite of DarkLight repos -- it is not in our repo, but in the collaboration set.
• Magnet: Ernie took the model from Harald and opened it, but was not able to extract what he needed. Once he has the pole and coil geometry, he can design the rest of the magnet, with the return yoke etc, that fits in the space allowed.
•  Ernie will iterate with Harald to get the magnet design moving
• Harald reports on the thin quadrupoles: He showed slides with the magnetic field calculations and maps, which have ~1% octupole components when zooming in closely. (Ernie described a rule of thumb trick for proportions of pole gap to poletip radius (R=1.15*G)). Harald's slides also show that the resulting geometry allows the spectrometer magnet to get wthin 22.5º of the beamline without issue -- and, in fact, the quad can be moved much closer to the target if desired. He concludes with parameters of the current design. Step files are also available (link). Jan points out our ultimate target of 16º, and we should see if that can be achieved.
•  TRIUMF (Thomas?) will look at Harald's design from the slides above. If all is well, we can start discussing who will make these.
•  Aveen will implement Harald's design into the ARIEL optical lattice simulation and see how it performs.
•  Doug will resubmit the poll for a new meeting time, since many could not respond before many of the times were grayed out.
• There was a request from Kate and Mike to fill in some info for the CFI process.

June 2, 2022 - Resurrecting this...

September 30, 2021 - General Meeting: https://indico.mit.edu/event/197/

• Discussed the cabling needed to put some basic radiation monitors near the test chamber. 18.6 m shv cables are the longest folks in Canada have found. Doug believes we have a supply of 5m cables, but these are minimally helpful. Conservatively, we'd like a 50m cable.
• The chamber and associated parts are in Washington state, waiting to cross the border (red tape).
• Mike et al. couldn't get access to the area yet last week (linac group still running), but now there's the 1 month shutdown, so should have access next week sometime -- will be able to look at the cable routing. Richard asks for a video of the area.
• Due to the Canadian holiday today, TRIUMF and SBU folks will push off their meeting on the administrative details of the workshop to next week, pending Jana's availability (vacation?)

August 19, 2021 - General Meeting: https://indico.mit.edu/event/149/

•  Ross will email the organizing committee to begin a separate discussion.
• Discussed the CFI grant strategy -- some discussion of how Darklight enables ARIEL upgrade and vice versa, funding-wise.
• The SBU side of the Moore grant has been resolved save waiting for a final signature. Original budget is expect to be accepted per the grant specifications. Now we need to start convening the actual Organizing Committee.
• Harald Merkel discussed the NINO readout board as it could be used to generate a high-resolution TDC. Readout through SoC FPGA/hybrid board, ~150$ per board.

August 12, 2021 - General Meeting: https://indico.mit.edu/event/148/

•  Ernie will talk with Chris to get the changes to the magnet to match expectations.
•  Jim, Ernie, Thomas, and Ben will discuss offline (and before the next meeting )the details of what the target chamber needs to mate with.
•  Thomas will connect us with the group that has been using fiber optic detector instruments in the hall.
•  Bob Laxdal will forward information on the temperature monitoring for ISAC
• NSF meeting on monday, Elena and Bill, seemed to go well. They cautioned against partial/split funding for postdocs for the possible complication of getting benefits etc. MIT gives full benefits if a postdoc is at least 50% funded. There was more follow-up discussion of how to most usefully split a post-doc across our institutions.
• Xiaqing showed some changes to the coil design that were made (link). The changes Chris made to the coil and yoke don't match what Ernie expected to be done. Thomas points out that the asymmetry seen in the y direction is a natural consequence of a C vs H yoke. Ernie agrees, and notes other ways to compensate this. Some of these have been applied to this design, but not all. -thomas planche brought up the installation which we hope to do in the september shutdown. Some notes: Beam goes from big pipe to small pipe. Size of the exit pipe is smaller than the beam aperture in the beamline. Jim notes we can supply a different chamber if needed. Just needs dimensions from Thomas: His requirement is no less than 2" diameter pipes. Thomas wants to avoid any small apertures that aren't instrumented to detect beam loss. The resulting chamber wants at least one observation port so we can point an IR gun at the target. They'll assume 18" plug in length and 4" up-stream and down-stream flanging. They need also a bellows on one side, and a superstructure (what does the bottom look like?). Bates will provide a structure at the right height -- just need to know the beam height. -how well can ARIEL currently measure and control the beam? Radiation monitors, beam monitors, steering etc? They have a variety of measurements, including a DCCT -The SRF requires high cleanliness, so we may need to install fast-acting valves, need to consider how to trigger them, in order to prevent contamination fromk damage to the target etc that would force a shutdown, stripdown, and reconditioning. Beampipe is all taken to be UHV -- 10-8 scale or better. -regarding using a quartz window, Thomas mentioned they'd had a window shatter due to radiation damage. Ernie points out that pyrex glass is not vulnerable to that same failure mode, and fiber optic is also possible.
  -Stan presented on magnetic field monitoring.

August 5, 2021 - General Meeting: https://indico.mit.edu/event/147/

ACTION ITEMS:

•  Xiaqing will implement the solidworks model from Ernie this evening, then send the results to Jan so he can look at the impact the modified current has on the resolution. This was done, but the model was not what was expected, so they need to iterate.

•  Ernie will ask where the 1B detector ended up (if it was still mounted when they went to Bates).  It was found at Bates.

•  Bobby is setting the 1B magnet to local control so that Ernie/Bates can run it (with a thermal camera) and see how much current it can accept.

• In terms of an experiment early next year, we could use the 1B scintillator patch -- ~5cm x ~10cm?, high amplification, SiPM readout. Details would be in Charles Epstein's thesis. More likely we would like a gem stack from michael (he says march is tractable). Rita has expressed interest in general, but not in time for that test, probably. Mike Hasinoff will look into what is available at TRIUMF, but probably nothing large enough to fully cover.

• We discussed also Jan's draft slides for the NSF discussion this coming Monday. One of the central questions from us for NSF is how to package a request for funding - as a single grant, or as individual institutions?

• Postdoc sharing between an US and a Canadian institution is probably not practical.

• The NSF meeting takes place at 3pm Eastern Time on Monday, Aug 9. The applications we make will depend on the outcome of that meeting (normal NSF deadline is December. These MRI grants are similar to a Canadian CFI )

July 29, 2021 - General Meeting: https://indico.mit.edu/event/146/

ACTION ITEMS:

•  Jim Kelsey will put together a pack-and-go and send it to Bob Laxdal cc some other useful folks, to show the scattering chamber and target ladder
•  Ernie will reach out to his contact to ask about the right window to use to get accurate temp measurements from outside the vacuum.
•  Ernie will send Xiaqing a new coil design. Xiaqing will calculate the field, and then pass to Jan to update the resolution plots
•  NSF meeting coming up. Jan requests that we lay out exactly which groups are responsible for what.
• We need to connect Bates eng. and TRIUMF eng still. Jim is on vacation starting shortly, but Joe Dodge should be invited to the next meeting. There is a separation at TRIUMF between accelerator and experiment physics, need some folks to help bridge that gap.
• Bob Laxdal put together a preliminary shutdown sheet and submitted it. It needs to be updated with more information. Hopefully those details are not urgent.
• Target ladder has a stepper motor that controls it, which can be done from the counting house. To read out temperature monitors etc we will need feedthroughs. Jim showed the chamber: Inlet tube is 3" diam, outlet is 1" diam. THere are a few mini-conflat (1.33"?) ports on the top of the chamber, alongside the ladder actuator. What is the right temperature sensor for this? The TDR contains the solution to the cylindrical heat problem. We discussed an IR/contactless interface. Need to make sure the IR light will pass through a window. ("7056 glass"?) Ernie knows this has been done at Bates -- but doesn't have a write-up handy -- of an infrared viewer that read out the temperature of a 600C crystal.
• Foils are 1,5,10um thickness. Jim hasn't opened the box yet (presumably verrrrry delicate).
• Xiaqing gave an update on the differences between Opera and Maxwell.
• Discussion of the readout devices. Are we talking SiPMs or PMTs? Jan suggests amplifiers can come from MUSE, and TDC can be done on an FPGA. The particular readout/detector design should wait for the magnet design and dispersion to be closer to final.

July 22, 2021 - General Meeting: https://indico.mit.edu/event/145/

ACTION ITEMS:

1. Bob Laxdal and Ernie Ihloff will discuss offline how to integrate the target: Who will provide the initial drawings, and who will return drawings with the interface specified.
2. TRIUMF will call a meeting when ready, to discuss with Bates engineers what resources (people) are needed to install the chamber.
3. Richard will send an email to Tomas (cc others) to lay out our intentions in order to get the plan for October moving (and reach the end-of-July deadline).
4. Doug will deliver the foils (which arrived recently) to Bates.

• Harald Merkel would like to join the collaboration, and called in today. There was some discussion of what magnetic field simulation codes A1 uses.

• Looking at when we would have to run the test experiment, and what should be involved. October, 2020 is the best time, since the next shutdown won't be until March. Vacuum chamber including a target ladder (with the foils) and temperature sensors would be a baseline. TRIUMF will need to see drawings of the chamber so they understand how to connect it, will need a description of what we intend to send. (interface to vacuum). TRIUMF uses MIDAS, though the 1B experiment ran with homemade software that was quite lightweight. For the October test, we would not expect to send a spectrometer magnet, just the scattering chamber, electronics, and various detectors to monitor backgrounds.

• Bob Laxdal described the shutdown procedures: By the end of July (give or take a few days), TRIUMF needs the shutdown project sheet filled in. with drawings, scope of work, resources (people) required. This ensures that when equipment shows up, TRIUMF has the people and resources to receive it. He can put in a placeholder sheet into the shutdown project, but wants a better estimate of what is needed. The advice was to be minimalist in the plan, so that the review board does not choose to punt the installation to the March shutdown.

• Canada is open for Americans to travel starting 9 Aug (and Canadians can come south starting 21 Aug). In a worst-case, we could ship the equipment and have Canadian collaborators manage the installation. If travel is possible and return is not in question, MIT will send people to guide/perform the installation. Jim notes that shipping has been particularly difficult lately, in terms of finding trucks and drivers etc.

• We need to clearly define the test experiment (counting houses, electronics, DAQ, detectors...). This needs to be fleshed out in the TDR

• Note that we need cables from detectors/controls to the 'counting house', in addition to having a counting house area defined.

July 8, 2021 - General Meeting: https://indico.mit.edu/event/143/

• Discussed stability and measurement of the magnetic field: Wwhat magnetic field stability do we need? How can we measure that? Ernie points out ~100ppm is very easy, current-wise. Stan Yen will write up something about how to measure field directly, at least from time to time, and about what we need in precision for our physics measurement, and what we can do to achieve that.

• Xiaqing has ansys maxwell installed and is simulating the field in the magnet now. She showed the application and various slices of the field. The magnet design shows us that the fieldlines route to left and right of the centerline in the steel, which is what we would expect. Ernie says he has tricks he can apply to widen the uniform region of the field in the bore.

• Ernie will give xiaqing some contacts to help with learning how to run the simulation -- there aren't good tutorials.

• Ross gave a brief tour of the wiki, which you are reading here.

July 1, 2021 - General Meeting: https://indico.mit.edu/event/142/ It is Canada Day, so some folks were not in attendance on the Canadian side.

• From last week, Mike Hasinoff has been nominated/put forward as the lead investigator on the Canadian side, with kate as the second-in-command. 
We discussed the CFI (Canadian Foundation for Innovation) grant that we believe someone has put forward. We're not sure who submitted, or what the context was, but DarkLight was referenced, per an email chain from Richard. That grant doesn't impact the test experiment, but only the The path forward is the same for us: We continue to plan for the test experiment, possibly this fall.
• Bates folks worked to remove the detector equipment from HVRL. Everything is back at Bates now, though not yet sorted. Hopefully the field in the existing magnets can be measured in the next week, so we can make more quantitative plans for the test experiment.
• Xiaqing Li worked on magnet simulations, now in a Win10 VM which she can run on her machine. She has been working on installing ANSYS on the VM, and has the physical dongle (but this didn't help with the installation). Probably an issue with the customer account. We reiterated wanting to involve TRIUMF in the magnet design. Rituparna suggests that they at least have codes they can share for the optimization.
• There was more discussion of the rotating target, the danger that might pose, and hence a question of how much current we can have without a rotating target. Jim Kelsey suggests using a magnetic coupling to the rotating target, so there is no issue of a coupling. a high-vacuum rated motor is also possible, though Jim points out these are generally low torque.
• We can put temperature sensors on the foil in the test experiment, to quantify the heating as we go. We might be able to defocus the beam., or raster/wobble in a known pattern that we can correlate to the bunches.

June 10, 2021 - General Meeting: https://indico.mit.edu/event/121/

• Jan discussed talks at a Heraeus conference: 8Be measurements being planned at INFN and elsewhere, and a recent Atomki carbon bump observation that might rule out axial vector coupling as a mechanism, though details are not yet available.
• A discussion will take place on Monday, June 21, at 1pm to discuss responsibilities and next steps for the canadian side of funding.
• Canadian travel still not clear, but should change/update on July 1.
• Richard highlights upcoming conferences we should consider abstracts for: DNP, PANIC. He will put together an abstract. There is also a Canadian conference (CAP?) where TRIUMF has given a recent talk, but it isn't clear who gave it or if DarkLight was mentioned.
• A proposal has been shared to use the PRad detector to search a similar parameter space.
• We agreed to set up a github wiki to see if it meets our needs. (This is that.) Not clear how to upload materials beyond images.