Minutes of the n tof collaboration and Collaboration Board Meeting Lisbon, Portugal 13-15 December, 2011

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Minutes of the n_TOF Collaboration and Collaboration Board Meeting

Lisbon, Portugal

13-15 December, 2011

Participants (group leaders and task responsible only):

Enrico Chiaveri, CERN (EC)

Roberto Losito, CERN (RL)

Vasilis Vlachoudis, CERN (VV)

Enrique Gonzales, CIEMAT (EG)

Daniel Cano Ott, CIEMAT (DCO)

Nicola Colonna, INFN (NC)

Marco Calviani, CERN (MC)

Carlos Guerrero, CIEMAT@CERN (CG)

Eric Berthomieux, CEA@CERN (EB)

Roza Vlastou, Un. Ath. (RV)

Laurent Tassan Got, IN2P3 (LTG)

Isabel Ferreira, ITN (IF)

Josef Andrzejewski, Un. of Lodz (JA)

Manuel Josè Quesada, Un. Sevilla (MJQ)

Vladimir Avrigeanu, IFIN (VA)

Helmut Leeb, Tech. Un. Vienna (HL)

Franz Kaeppeler, KIT (FK)

D. Bosnar, Univ. Of Zagreb (DB)

P. Schillebeeckx, IRMM (PS)

W. Mondelaers, IRMM (WM)

D. Schumann, PSI (DS)

C. Lederer, Univ. of Vienna (CL)

P. Milazzo, INFN-Trieste (PM)

P. Woods, Univ. of Edinburgh (PW)

J. Billows, Univ. of Manchester (JB)

Welcome remarks

EC and EG introduce the meeting, by thanking the ITN team for organizing the meeting. Isabel Goncalves and Pedro Vaz welcome all participants and give some more details on the organization.

EG proposes to approve the minutes of the last Collaboration and CB meeting. Apart for some minor correction, there are no objections, so the minutes are approved. EC asks NC to take the minutes of the present meeting, once more. He then invites FG to chair the first session, on the data analysis.

Status of data analysis

F. Belloni presents the latest results on the beam profile. The analysis has been refined, and the width of the beam is now given directly or as a result of a 2D Gaussian fit. From the width, the Beam Interception Factor has been determined. At present, the agreement between experimental results and simulations is still not satisfactory. In particular, the experimental results show an unexpected trend as a function of neutron energy. Several comments are made, but no final conclusion is drawn. Belloni will continue investigating the problem.

A. Tsinganis shows the results of the simulations on neutron fluence, beam profile and time-to-energy relation. He explains in details the geometry implemented in the simulations and the influence of various effects (gravity, collimator misalignment etc…) on the results. On the time-energy relation, he shows that a simple correction with a time offset, t0 , works only up to a few hundred keV (with t0 for the new target more than double that of n_TOF-Phase1). For high energy he suggests to use a correction taken directly from the simulations at each energy. This has been validated with the Al dip in the flux and with some fission data at higher energy. NC objects that the experimental validation is not as good as it was done in n_TOF-Phase1, and that at high energy the effect may not be so important. AT will make available the time-energy relation from simulations.

CG shows the results on the experimental determination of the neutron flux. All effects have now been taken into account, including attenuation in the material along the beam, and anisotropy effects in 10B. The agreement between various detectors is now very good, and also with simulations the agreement is not bad, except in some absorption dips. It is estimated that the uncertainty in the flux is typically 2-3% in most of the energy range. The results are final and they are available as Root file.

On the analysis of the 10B Micromegas, Maria Diakakis shows the results of some simulations she has performed in order to understand the effect of the discrimination between Li and alphas on the determination of the flux. She shows that the spectra relative to the two reaction products in some neutron energy regions overlap, and this makes difficult to estimate the flux from the a-particles only. One possibility she suggests is to take into account both Li and alpha in the analysls.

C. Lederer reports on the analysis of 63Ni. The run was very successful and the analysis is advancing fast. The 63Ni contribution is well above that of 62Ni, which contaminates the target. There is still some work to be done, for example on normalization, to improve the accuracy of the results. On the same issue, M. Weigand from Frankfurth shows the results obtained at Los Alamos. The main features are similar, but the resolution is worse and there could be also a higher effect of the neutron sensitivity, since the detector used was the 4 BaF2 calorimeter, instead of the C6D6 detectors used at n_TOF.

G. Giubrone presents the status of the analysis of capture of various Fe isotopes. The work is well advanced on most of the measured isotopes. Few details are still pending, such as the inclusion of the final flux and, most importantly, correction for the threshold and neutron sensitivity. On this respect, GG informs that he is trying to estimate the neutron sensitivity by means of simulations. At present reasonable results have been obtained for the detectors alone, while the next step will be to include walls and other material.

J. Praena reports on the few data taken on the 33S(n,) reaction. He shows details on the fabrication and characterization of the sample. A very careful job was made, with several tests before finding the right procedure. The sample was characterized by RBS analysis before being mounted inside the Micromegas detector. He shows some (very few) data taken before the beam was stopped due to a problem with the PS. The signals and preliminary yield seem very reasonable, although with low statistics. Some tests were made to try and understand the right dimension of the gas gap in the MGAS. Since the test beam has been very successful, he is ready to submit a proposal for the full measurement, to be performed in 2012.

V. Konovalov presents the results of the fission cross section measured with the FIC detector in 2002, on 234U and 237Np (those results will be part of a PhD thesis he is preparing at Univ. of Vienna). He provides some details on the analysis and shows the results. For 234U, the results he has obtained are compatible with those from PPAC, already published. On the contrary, for 237Np his results differ, by approximately 8%, relative to the PPAC ones. However, he estimates that the systematic uncertainty on his results are between 6 and 7%, so that the FIC results could still be compatible with the PPAC ones. NC suggests to consider the new results for the shape of the cross-section, rather than in absolute value.

A Tsinganis reports on the status of the 240,242Pu measurement, with the MGAS. Apart for some initial problems on a couple of electrodes, the measurement has run smoothly, and some data have been collected in parallel with capture measurements, for a total number of protons of 5x1018. This is less than the number requested, 8x1018, and furthermore one should consider that the size of the samples and of the beam is smaller than originally predicted. Therefore, the statistics is much smaller than expected. For 242Pu data have been processed, and some results above threshold have been obtained, which look reasonable. For 240Pu, the a-activity is too high and a special signal reconstruction routine has to be used. At present there are no results on this isotope. AT also shows the status of simulations on the energy deposition inside the MGAS and on the signal formation. Such information could result useful to understand the response of the detector to a-particles and fission fragments, even in a high count-rate environment.

K. Fraval presents the on the capture cross section of 241Am measured with the C6D6. The analysis is well advanced. All background components have been estimated and subtracted, although some residual component may still be present. The data have been normalized to Au, and resonance analysis has been performed. Some new resonances have been introduced to improve the fits. To complete the job, the resonance analysis has to be refined up to 300 eV, plus the statistical analysis has to be done. Finally, the analysis of the Unresolved Resonance Region will be performed next. Peter Schillebeecks asks some questions on the background determination and subtraction, while NC comments that the filters may produce some extra background that may affect the measurement. KF will consider these questions in the follow up of the analysis.

M. Barbagallo and M. Vermeulen present the current status of the analysis of the capture cross section of 236U, performed with the C6D6 and the TAC. In both cases the measurement was successful, and the analysis is now starting. In the case of the C6D6, there is the potential for obtaining cross sections from thermal to 1 MeV, while the range covered by the TAC will be smaller, due to the influence of the -flash to larger times. The TAC will also be affected by a larger dead-time correction.

T. Wright presents the status of the 238U capture cross section measurement with the TAC. The experiment was successfully completed, and apart for the usual -flash problem above a few hundred keV, the preliminary results look promising.

D. Tarrio reports on the measurement and preliminary analysis of the angular anisotropy of fission fragment emission in 232Th(n,f) and 234U(n,f) reactions. He describes the setup and the analysis procedure used, and shows the first results on Th. The new results are in good agreement with previous data, but extend to higher energy. Fine structures cannot be resolved due to the poor statistics, but with more data it should be possible to investigate further those structures. VK asks if it is possible to study the anisotropy as a function of the fragment mass, but the problem is that the masses cannot be separated.

C. Weiss reports on the test of the diamond detector for (n,) reactions. She describes the pCVD detector and the sample of 10B used for the measurement, which was characterized at Sevilla by RBS analysis. The flux impinging on the detector was estimated by means of a Au foil activation. The detector was calibrated with an 241Am source, and the background was measured and subtracted. Relative to what expected on the basis of the simulations, the efficiency of the device resulted to be much smaller, and this was attributed to a poor quality of the diamond material which was responsible for a much degraded signal of the energy deposited. This was also evident by examining the material itself, and noticing some graphite inclusion. For 2012 there are two possibility to improve the situation: a very accurate quality check on the material (with smaller thickness) or a completely new material that is now becoming available, which should have the same features of single-crystal diamonds, but with an area much larger.

A. Ventura presents a new set of calculations performed with the EMPIRE code for the fission cross sections of several actinides. He describes the formalism used, and the inputs in the code, which are related to the physics of fission process. This work originated from the need to better reproduce the trend observed in recent fission cross section measurements at n_TOF on two Am isotopes. The model used in EMPIRE can and will still be improved. Ventura reaffirms that the n_TOF data could be very useful in the optimization of the code. This is the case, for example, of the 234U fission cross sections and its angular anisotropy that is being determined at n_TOF. Several questions on the details of the model and of the code clearly testify of the interest of the n_TOF Collaboration for this very important work.

FK presents the status of publications at n_TOF. For capture, the number of published papers on the data from n_TOF-Phase 1 is impressive, with only a few commitments still pending. For fission cross section measurements, there has been an improvement in the last two years, and several papers have now been published. Finally, FK shows the list of papers in preparation, and he puts forwards some ideas, like making a flyer for n_TOF and publishing a paper on the upgraded facility. He then reminds that publishing the data is not the end of the story, since they have to be made available to the community via Exfor. For this aspect, he reports that Tim Ware has volunteered to act as interface between n_TOF and EXFOR. He will be the reference person of the collaboration for checking the correctness of existing entries in the database, and for submitting new data and documentation. As a first step, the contact person for each dataset should be identified and contacted.

Test measurements

The next session is dedicated to test measurements performed at n_TOF in the course of 2011. Rogelio from Univ. of Sevilla reports on measurement on FBG dosimeters (optical fibers), whose response changes with the absorbed dose. The test was performed for a few days, in vacuum (FIC chamber), and it should continue in 2012. M. Calviani informs that there are other irradiation facilities at CERN where the test could be performed, on charged particles. Another test was performed by P. Woods, from Edinburgh, on Si detectors (mounted in the SiMon chamber) to check the feasibility of light-charged-particle detection at n_TOF. The aim would be to study the 26Al(n,p) and (n,) reactions, of interest for astrophysics. The test was successful, and evidenced no particular noise problems, even connected with the -flash. The last test was proposed by the Kyushu Univ., to study the response of an E-E telescope made of plastic scintillators plus BGO, to be used for studying (n,d) and (n,) reactions at GeV neutron energy. Some data were collected, showing signals in correspondence of GeV neutrons, but to avoid the strong influence of the -flash, the detectors had to be moved far away from the beam direction. Before drawing conclusions on the feasibility of the measurement, more analysis is needed.


EC shows a list of samples that have been procured for the measurements so far, mostly from IRMM, and a list of many more samples that could be available from Univ. of Munich. Some of them are short-lived, and could be measured at the EAR-2. In any case, the n_TOF Collaboration is trying to establish contact with several Institutes and Organization, like IRMM, Univ. of Munich, ORELA, CACAO, PSI etc… for the production of high purity samples to be used in measurements at CERN. On this respect, three presentations follow: a very interesting possibility for the production of exotic target could be offered by the RadWasteAnalytic group of PSI, which has already been very helpful so far for the preparation of the 63Ni sample. At PSI there are several sources of radionuclides, from accelerator waste, spallation neutron source, special irradiation, etc… She shows some instructive examples and describes the procedure used for the sample purification and preparation. At the end, a list of possibly interesting radionuclides is shown, among which is of particular interest the production of 7Be samples (for Big-Bang Nucleosynthesis experiments). DCO says a few words on the contacts ongoing with the Oak Ridge laboratory, for some specific samples. The reference group has been identified and work is in progress to finalize the framework for the sample procurement. A list of material of possible interest for n_TOF has been submitted to Oak Ridge, and he is optimistic that in the near future some samples could be obtained through them. As for CACAO, LA reports that things are progressing with authorization and preparation of the target laboratory, although some delay has to be expected. Nevertheless, some samples have already been prepared and characterized, such as 232Th.

Proposals for future measurements (2012)

Univ. of Santiago de Compostela and IN2P3-Orsay present the request for 236U and 234U fission fragment angular distribution measurement, that could be performed in 2012, while the idea of measuring 231Pa next year does not seem to be realistic. The request for the measurement is 3x1018 protons, with several 234U, 236U, 232Th samples, as well as 235U.

CW presents the proposal for the 59Ni(n,) measurement with diamond detector. The motivation is Astrophysics and nuclear technology, but she would also like to demonstrate that such detectors are suitable for measuring (n,) reactions at n_TOF. The proposal aims at collecting data with 2% accuracy. In the light of the 2011 measurement of 10B, the feasibility of this measurement is still not clear. NC suggests to collect some data for this reaction with the MicroMegas detector, which have been proved to work in the 33S(n,) measurement. CW announces that new diamond device with better performance are now available and will most probably be used in the measurement. On this regard, a recommendation is made to setup and test the detectors in the lab before the experiment.

NC shows some test measurements proposed by some external groups, on single-crystal diamond detectors and Bonner sphere. The tests are proposed by several Italian Institutions, like CNR, Univ. Tor Vergata Roma, INFN, etc.. All these tests should be performed in parasitic mode, possibly in the escape lane, in order not to affect the main measurements. The proponents will take contact with the smokesperson to define the details of mechanical mounting, acquisition systems and running period. A similar test, on a BGO detector, is presented by EC, on behalf of another Italian group from Rome.

PW presents the proposal on the 26Al(n,charged particle) reaction, based on the success of the detector tests. In principle, the experiment could be performed in 2012, by mounting the apparatus in the experimental area and taking data for the whole running period. This is however considered not very feasible, and anyway at the end the statistics would still be small. It is suggested that such an experiment could ideally be performed in the EAR-2, but it is agreed that some more test should be performed in EAR-1 in 2012.

C. Massimi presents a proposal for the measurement of 25Mg(n,) cross section. This reaction was already measured in n_TOF-Phase 1, and the results are now in the process of being published. However, there is a strong suspicion that the mass of the 25Mg sample might have been wrong, by as much as 30%, due to water contamination. A new, enriched sample has been now located and could be available for making a more accurate measurement in 2012, both at n_TOF and IRMM. The same astrophysical motivations are also at the basis of a measurement of 25Mg(n,) reaction. This however cannot be performed in EAR-1, due to the very thin deposit needed for the detection of very low energy alpha particles. This reaction could instead be studied in EAR-2, which in fact would be a unique place for such kind of measurements.

A final measurement, for the characterization of a new Silicon detector under fast neutron irradiation is presented by Rogelio, Univ. of Sevilla. The test should be performed in the escape lane of n_TOF, in parasitic mode.

The making of EAR-2

EC presents the motivation, design and status of the proposal for EAR-2. A first draft of the document has been sent to the Collaboration Board, and he is now expecting comments on the various parts of the proposal. This has to be ready in a few days, to be submitted to INTC. EC shows the scientific case, which is in line with the core business of the n_TOF Collaboration (Astrophysics and Applications). On top of that, a special position near the target along the vertical flight path could be used for dosimetric and radiation damage studies. He then shows the current status of the design of the main parts of the EAR-2, the dose calculations for a possible choice of the collimator and beam dump, and of the geometry of the experimental area. A lot of preliminary work has been done, showing the feasibility of the new area, but a final design has to be produced, if and as soon as the proposal for the new area is approved by CERN. As for the cost of the new experimental area, at present this is estimated in over 3 MCHF, and will require at least 9.3 Staff FTE. He states that resources should not be a big issue, if CERN agrees on the opportunity to go ahead, and he has already initiated some preliminary negotiation with the management. It is envisaged that the costs would be shared almost equally between CERN and the Collaboration. Both FG and NC remind that the Collaboration has also to make an extra effort for building and setting up monitors, detectors and acquisition systems for the new experimental area, and that such effort should be considered in the total cost of the enterprise.

As for the proposal, EG suggests to add a few more figures in the final version, to show the full model of the various parts of the EAR-2, on which calculations are based.

CW shows the latest simulations on the performances of the new facility, in terms of flux, resolution function, contamination of charged particle, -flash, etc… The simulations have been performed for EAR-2 at 18.4 m, with a collimator in place and with and without additional moderator on top of the target. The energy dependence of the neutron flux is similar to that of EAR-1, with a maximum gain of 27 (and fewer high-energy neutrons). The resolution worsens by an order of magnitude, and can be improved by adding some moderator (with a 30% decrease in flux). The charged particle fluence shows a maximum momentum around 1 GeV/c, which would require a magnet (possibly permanent) of 0.2 T (1 m long). The in-beam contamination is comparable to the one in EAR-1, but it affects a much lower neutron energy range, where cross sections are typically higher. On the contrary, the -flash extends down to lower energy, due to the shorter flight path. However, its magnitude is smaller, in particular relative to the much higher neutron flux. The spectrum of prompt -rays is also different, with essentially no high-energy -rays in EAR-2. The beam profile with the collimator is shown, together with the background caused by backscattering from the beam dump. The situation is clearly worse than in EAR-1, but it does not seem to pose critical problems. CW finally presents the available flux at 1.5 m, for an irradiation facility. DCO asks about the height of the beam dump. This has been chosen a compromise between various factors, including costs and complexity, but there is no final decision yet and if necessary the final design could be modified.

AT presents a more detailed study, with simulations, of the -flash, in-beam -rays and effect of the collimator on EAR-1. This study is useful to provide a reference for the performance of EAR-2. One possibility is that in the so-called -flash there could also be a component of charged particles and -rays produced by interaction of high-energy neutrons in the second collimator. To be more realistic, AT has included in the geometry the detectors in EAR-1. The simulations clearly show that there are events with high energy deposition in the detectors, which are due to charged particles and -rays produced in the 2nd collimator area which could be responsible for part of the observed -flash in the detectors. Clearly, such an effect could also affect the -flash in the EAR-2, and should be further investigated to optimize the collimator design and estimate the magnitude of the effect. Various questions arise on the fraction of the events that could be attributed to charged particles and -rays produced in the 2nd collimator, on the directionality of the background, etc… All these effects need to be further investigated.

EC shows more in detail the scientific motivations at the basis of EAR-2. In general, the higher flux combined with the shorter time-of-flight would allow one to perform experiments with very low mass samples, thus opening the way to measurements on radioactive isotopes with short half-life, even down to a few years. Furthermore, it could be possible to measure isotopes with very low cross sections, in a much shorter time. Finally, the prediction of a smaller -flash (to be confirmed by tests) may allow to extend the range of measurements to higher energy. He then goes in some more details of the motivations. From the point of view of applications to nuclear technology, in particular for transmutation of nuclear waste, EAR-2 could allow to measure several short-lived actinides, while on the Astrophysical side it would be possible to measure several branch-point isotopes which are currently very difficult to measure (or to get samples of the needed mass). Neutron-magic isotopes, which typically have very low cross sections, could be measured in a short time, while for some s-only isotopes high accuracy of 2% could be easily reached in a reasonable time. The possibility to use small mass samples could also make possible measurements of (n,charged particle) reactions of interest for stellar nucleosynthesis, which require thin samples. He mentions that several letter of interest have already been prepared for measurements to be performed in EAR-2, and they have been included in the proposal to be submitted to INTC. NC mentions that he is thinking about a new measurement on 7Be, of interest for Big-Bang Nucleosynthesis, but had no time to prepare it yet. EC invites him to make any effort to prepare the letter of intent in a week or so. NC suggests that the proposal of 26Al(n,), from Edinburgh, could also be an additional letter of interest, since EAR-2 would be ideal for performing that measurement. DCO remarks that it is important to show the interest of various groups to perform the measurements, and for this reason it is important to include the letter of interest in the proposal. A final remark on the feasibility of the measurements. In cases in which new devices or techniques are going to be used, test should be performed on the detectors, if possible in EAR-1. This is the case, for example, of a proposal in which Ge detectors could be used.

DCO shows the work being done at CIEMAT on new flash ADC digitizers, to be used in a different project, but that could be of interest for the collaboration for the setup of the acquisition system in EAR-2. The performance and costs of the new digitizers would make them attractive relative to currently commercially available FADC.

The last part of this session is dedicated to the work to be done in the near future to finalize the design of EAR-2 and to task assignment. There is a large amount of work to be done, if the proposal is approved, to complete the design and optimize the neutron beam optics, and people are needed to help with calculations of the background in the experimental area. It is important that the Collaboration starts already thinking about the detectors to be installed in the EAR-2 and the new acquisition system.

DCO mentions that at CIEMAT they have the intention of making some simulations to see if the performance of the facility could be further optimized with some minor modification of the design, They also plan to investigate possible alternative solutions for the detectors to be used for a new TAC. It is remarked that it is the time to start thinking about organization of the Collaboration for all work concerning experimental systems.

A general discussion takes place on the EAR-2. RL remarks that CERN management knows that Institutes right now are not in the position of commit for money, since the facility has not been approved. However, it is important that the Collaboration agrees that, once approved, all Institutes will make any effort to participate to the maximum of their possibilities to the manpower and financial request for the preparation of the EAR-2. EC ends with the road-map for the proposal: in February there will be the discussion within the INTC, and if approved, the proposal will be examined by the Research Board at the end of February. If approved at that point, it would be the official start of the EAR-2 project.

EG suggests to make clear that the Collaboration strongly supports the scientific case for EAR-2, and that there is very high interest towards this new facility for the opportunities of new research it would offer. It will be necessary, especially if and after EAR-2 is approved, to commit people from the Collaboration to continue the work. To his view, all Institutes should commit to participate to the effort at the best of their possibilities. EC remarks that the spirit of this new enterprise is to provide new results in conjuction, and not in competition, with other facilities that are now being proposed and built. It is also important to remark that in principle EAR-2 could start producing results in a reasonably short time, in a moment in which other facilities may be facing problems in being completed. In any case, the word to keep in mind is “complementarity” between the research activity to be done at n_TOF/EAR-2 and the one that could be carried out elsewhere.

Collaboration Board

The minutes of the last Collaboration Board are approved, with some minor changes on the participant list.

EB presents a status of the n_TOF facility (including EAR-1). In general, in 2011 there have not been major problems, and only a small maintenance on the target/cooling system and on the interlock for access is necessary. All this action will be performed during the shutdown. There will be also some intervention in the experimental area to understand and possibly cure the problem with the grounding, which is responsible for some noise observed in particular as oscillations after the -flash.

NC reports the status of the finance. In 2011 there have been few expenses, thanks to a bigger support from the CERN group in running the experiments. This has resulted in some funds saved, in view of the financial effort for the construction of EAR-2. The M&O contribution from the Institutes has been mostly collected. Apart for the Spanish Institutes, which will now follow a different procedure, only few Institutes have not yet complied with their obligations. Some of them have in fact never complied so far, and NC poses the question on whether they should be considered as part of the Collaboration. EC will contact these Institutes, one by one, to check if there is a possibility that they could start contributing, even with a different mean, to the Collaboration effort. A discussion takes place on the possibility for the Collaboration to contribute to the cost of EAR-2. According to the present budget and predictions for the next two years, it will be difficult, according to NC, to reach the level requested, especially if some funds will be also needed for building the detectors and acquisition systems. It may be necessary to ask the Institutes for an extra financial effort, but it is premature to foresee such additional contribution, given the difficult economic situation of almost all Institutes and the fact that the costs of EAR-2 have not been finalized. It is also hoped that a further negotiation with CERN will make things easier for the Collaboration.

EC presents some key points on the document to be sent to INTC for EAR-2. Some corrections are proposed to the phrasing, to make more clear the advantages of EAR-2. For example, it should be make clear the new feature of the facility, i.e. an instantaneous neutron rate 250 times higher than for EAR-1, “while maintaining the features already present in EAR-1, in particular the possibility to measure neutron induced reactions up to high neutron energy”. It should also be explicitly said that the new area is suited for low cross section measurements and (n,charged particle) reactions. Finally, on the last point, it should be mentioned that the irradiation facility is of interest for other applications, such as dosimetry, various material tests, devices, detector development etc….

A formal statement of suppot from the Collaboration is approved: “The n_TOF Collaboration Board in the meeting of Lisbon on December 15th, 2011, strongly support the construction of a second experimental area at a shorted flight path, and is willing to participate in the effort, assuming that civil engineering and beam line contraction activities could be covered by extra contributions from CERN budget (see Appendix 1 on document “Proposal for n_TOF Experiment Area-2 (EAR-2)”.

The Collaboration supports the formulation of this sentence.

Planning of 2012

EC presents a tentative planning for experiments in 2012. The total request, including proposals to be submitted to INTC, is 1.9x1019 protons, to be compared to the expected number of 1.6 x1019. However, at present it is not necessary to rearrange the plan. If necessary, some measurements could be combined, some postponed and some shortened. A more realistic plan will be made in spring, on the basis of the situations of the various experiments. A tentative list of priorities is discussed, with the measurement on 87Sr assigned the lowest priority. FG mentions that there is a new PhD from INFN that is interested in analyzing the 238U data that will be collected in 2012 with C6D6 detectors. CG mentions that among the proposals to be submitted to INTC one should also consider 33S(n,), which was originally sent as a letter of intent, but is now in the condition to ask for beam time. Most probably, the 2012 campaign will start with capture cross section measurements, and as usual we will switch to fission in the course of the year. DE and LTG strongly suggest this year to avoid switching at the last minute, since the experience of past years teaches that if there are problems with the beam at the end of the year it is not possible to recover. The fission program needs more data and effort should be made to make sure that they the requested statistics is collected.


EC mentions that three more Institutes are officially entering the Collaboration. One of them is IRMM, for which all legal aspects of their participation seem now to have been solved. NC remarks that IRMM is not a new Institute, but has always been collaborating with n_TOF, since the beginning, and that now such collaboration should only be strengthen. EC reminds that IRMM is providing some samples, but in the past some confusion has arisen from the n_TOF side. From now on, Peter Schillebeeckx is the contact person at IRMM for sample preparation.

R. Dessler for PSI presents the group and its activity and the interest in joining the collaboration. The main task of the group within n_TOF will be to support the Collaboration in the procurement, purification and preparation of some particular samples, on the example of what has already been done for 63Ni. EC on behalf of the whole collaboration states that this collaboration is important, since it can provide very valuable radioactive samples, and is willing to support the new PSI group to all extent.

The third Institute to join the n_TOF Collaboration is Univ. of Frankfurt. C. Lederer, which will soon join the group, shows a few slides on the composition and activity of that group. It is quite a large group, working mostly on Nuclear Astrophysics. It has several interests and making experiments in various facilities, like Los Alamos. It is also responsible for a future neutron facility, FRANZ, and is also working with radioactive beams. Finally, it is working on new detectors, in particular for neutrons.

CG presents a few slides on the activity of the analysis group. This has been operating in 2011, with periodic meetings organized to discuss on the progresses and find a common way to proceed. For 2012 the group will continue in the same way, with two dedicated meetings, in spring and fall, and perhaps another meeting during the general collaboration meeting in December.

A discussion takes place on the Editorial Board. In general only a few people of the EB seem active, providing comments and suggestions to the various papers. It is therefore suggested to add more people that could contribute more actively. The proposal is to add Carlos Guerrero and Peter Schilebeekx. The proposal is accepted.

Author list

At present there is some confusion on which author list should be used when preparing a new paper. There are lists for the first campaign, different lists for the phase-II, and each year the situation changes with the addition of new Institutes and of several PhD students. It is decided the a revision of the list year-by-year should be done, and that the EB should review such lists and decide on the authors. For the moment, the author lists should be maintained by Eric Berthoumieux.


EB gives a report on the shifts made by each Institute in 2011. After reminding the rule adopted, which seem to have avoided criticisms in covering the shifts in particular over night and in weekends, he shows a table with the percentage of shift completion for each individual Institutes. Many of them have provided more than 100% of their allocated shifts, while a few Institutes have done little or none. For 2012, the running period will be from March 19th to Dec. 3rd. Consequently, the number of shifts will be slightly larger than in 2011, with an average of 12 shifts per person instead of 11.5 of 2011. A tentative shift allocation for each Institute is then presented.

Next meeting

EC suggests to have a meeting in April at CERN, while for the general one at the end of year possible candidates are Manchester, and one Institute in Italy (to be announced). In case of problems, it would also be possible for CERN to organize the end-of-the-year meeting. At last, before closing the meeting, EC thanks the ITN-Lisbon group, and i.e. Isabel Ferreira, Raul Sarmento, Carlos Carrapico, and Pedro Vaz, for a great job with the organization of the meeting. He also thanks the n_TOF CERN crue, in particular Carlos, Eric, Christina, Andrea and Marco for their unique contribution on running the experiments and for the outstanding work on Exprimental Area 2.

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