ELOG CRIB

AIDA GELINA BRIKEN nToF CRIB ISOLDE CIRCE nTOFCapture DESPEC DTAS EDI_PSA 179Ta CARME StellarModelling DCF K40

CRIB

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Entry time:	Fri Mar 28 20:45:05 2025
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> In today's meeting, the following points were discussed / revised / added considering the Inventory and Status eLog. > > Simultaneously I discuss today's work where applicable. > > === F0 === > > We will probably not use the carbon stripper foil. Although it would be interesting to confirm (or finally refute) the Leon charge-state distribution model for work at CRIB, > the stripper foil lifetime probably cannot be more than several days of beam. E.g. in 30S experiment, a 2.5 um Be foil was broken by the primary beam after only a couple of > days (28Si at 205 MeV and 70 pnA). We do not have very many foil mounting positions to put in ~5 stripper foils to F0. Moreover, we got ~10^5 pps of RIB at F3 in the test > experiment, but the ion source operation was not good, and we are expecting >=5 times more primary beam intensity in the main experiment. Thus if the stripper foil really > works well (factor 5--10 higher 26Al13+ intensity) we would have over 10^6 pps which the PPACs (and probably DAQ) cannot handle. Once the stripper foil breaks, we need to > retune Brho which means our RIB production optimization is lost and needs to be partly redone (several hours of work, perhaps). I will check some stripper-foil lifetime papers > this weekend, but empirically for CRIB energies I think we know the answer. > > === F1 === > > It was unanimously agreed not to open F1. > > === F2 === > > The BRILLANT+C project requested some measurements for the machine time in April. F2 was opened in the afternoon and the measurements were made. We will still plan to check > the F2 PPAC and F2 SSD next week. > > === F3 SSDs === > > Now all the circuit boards for the Edinburgh SSDs are made, and after some further modification, it was confirmed that there is not cross-talk between X and Y sides. > > Although we did not check any local SSDs or the list, CRIB local members were of the opinion that there are a sufficient number of SSDs for three telescopes. > > We replaced the beam-left pre-amplifier Faraday cage with a larger one. Yamaguchi san found the spare PA chips. All channels were tested, and we have 96/96 working channels. > One PA box was found to have ~2.5x higher gain (so amp setting shall be lower for that one). The PAs were roughly installed into the Faraday cage as well. > > In addition to the 207Bi beta source of RIBF, CNS has the following sources: > 60Co (x2), 90Sr. The RIPS 22Na is also a beta source. > > We decided not to measure 26Al beam energy at F3. One point that was overlooked in the previous eLog is the time required to calibrate an F3 SSD for heavy ions. If we decide > it is really necessary to make such a measurement, an appropriate circuit could be constructed during the beam time in under 1 hour. > > Splitting the PA signal to two amplifiers for the forward-angle thick SSDs seems like the best option for measuring both protons and positrons, so we will try that. We will > use a common TFA, however (so the PA signal will be split 3 ways rather than 2 ways). > > Because the zero-degree telescope is very close to the chamber wall and will have 4 layers (rather than 3 from the machine test), we decided to install the small pipe (~10 cm > length) between the chamber and the flange. This will give a little more space for the detectors and cabling. We did it after the meeting. > > === F3 NaI === > > The spectra in the logbook were showing the situation before Pb shielding was added to block radiation originating from the beam line pipe. We should print the new spectra. > > Since the CAENNET is working, we don't need to use the local keyboard and monitor. Instead we can connect via a laptop. This should help to ease congestion around the F3 > chamber during preparation, since much of the NaI work can be done anywhere in E7 or J1. > > === F3 Targets === > > The five targets planned for use are: > 30+50=80 um CH2 > 11 mg/cm^2 Carbon > Blank target > Al block > Plastic block > > The new target mount, Al block, and plastic block are expected to arrive from the company early next week. The Al block used in the test experiment had many holes in it > (though it was covered with Al foil and tape to ensure at least the RIB is stopped). This may explain minor discrepancies between the data and the GEANT4 simulation. Plastic > will be used in addition to Al because it has less attenuation for gamma-rays, which may also help to understand the 511 keV gamma-ray data during the half-life (isomeric > purity) measurement. > > === F3 PPACs === > > Today, alpha-4 source was placed in F3, both PPACs were moved to the "in" positions, covers were removed, and masks applied. We evacuated the chamber. Within ~1 hour, already > the vacuum level is 1 x 10^-2 Pa. > > === Other === > > On 2.27, some workers will come to install a new hydrogen gas level detector near F0. We should try to avoid doing alignment on this day, at least when the workers are > present, since they could disturb the laser position by accident (although, it is the ideal day for alignment based on the beam time schedule...!) Encoding: HTML ELCode plain Suppress Email notification

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